diff --git a/ethcore/src/client/client.rs b/ethcore/src/client/client.rs
index b5d572535..8a294f4fd 100644
--- a/ethcore/src/client/client.rs
+++ b/ethcore/src/client/client.rs
@@ -368,7 +368,7 @@ impl<V> Client<V> where V: Verifier {
 					invalid: invalid_blocks,
 					enacted: enacted,
 					retracted: retracted,
-				})).unwrap();
+				})).unwrap_or_else(|e| warn!("Error sending IO notification: {:?}", e));
 			}
 		}
 
diff --git a/sync/src/lib.rs b/sync/src/lib.rs
index c3935f5e1..e54447d44 100644
--- a/sync/src/lib.rs
+++ b/sync/src/lib.rs
@@ -154,11 +154,13 @@ impl SyncProvider for EthSync {
 	}
 
 	fn start_network(&self) {
-		self.io_channel.read().unwrap().send(NetworkIoMessage::User(SyncMessage::StartNetwork)).expect("Error sending IO notification");
+		self.io_channel.read().unwrap().send(NetworkIoMessage::User(SyncMessage::StartNetwork))
+			.unwrap_or_else(|e| warn!("Error sending IO notification: {:?}", e));
 	}
 
 	fn stop_network(&self) {
-		self.io_channel.read().unwrap().send(NetworkIoMessage::User(SyncMessage::StopNetwork)).expect("Error sending IO notification");
+		self.io_channel.read().unwrap().send(NetworkIoMessage::User(SyncMessage::StopNetwork))
+			.unwrap_or_else(|e| warn!("Error sending IO notification: {:?}", e));
 	}
 }
 
diff --git a/util/src/io/service.rs b/util/src/io/service.rs
index 65be55540..07e60f766 100644
--- a/util/src/io/service.rs
+++ b/util/src/io/service.rs
@@ -135,8 +135,9 @@ impl<Message> IoContext<Message> where Message: Send + Clone + 'static {
 	}
 
 	/// Broadcast a message to other IO clients
-	pub fn message(&self, message: Message) {
-		self.channel.send(message).expect("Error seding message");
+	pub fn message(&self, message: Message) -> Result<(), UtilError> {
+		try!(self.channel.send(message));
+		Ok(())
 	}
 
 	/// Get message channel
@@ -351,7 +352,9 @@ impl<Message> IoService<Message> where Message: Send + Sync + Clone + 'static {
 	/// Starts IO event loop
 	pub fn start() -> Result<IoService<Message>, UtilError> {
 		let panic_handler = PanicHandler::new_in_arc();
-    	let mut event_loop = EventLoop::new().unwrap();
+		let mut config = EventLoopConfig::new();
+		config.messages_per_tick(1024);
+    	let mut event_loop = EventLoop::configured(config).expect("Error creating event loop");
         let channel = event_loop.channel();
 		let panic = panic_handler.clone();
 		let thread = thread::spawn(move || {
@@ -390,7 +393,7 @@ impl<Message> IoService<Message> where Message: Send + Sync + Clone + 'static {
 impl<Message> Drop for IoService<Message> where Message: Send + Sync + Clone {
 	fn drop(&mut self) {
 		trace!(target: "shutdown", "[IoService] Closing...");
-		self.host_channel.send(IoMessage::Shutdown).unwrap();
+		self.host_channel.send(IoMessage::Shutdown).unwrap_or_else(|e| warn!("Error on IO service shutdown: {:?}", e));
 		self.thread.take().unwrap().join().ok();
 		trace!(target: "shutdown", "[IoService] Closed.");
 	}
diff --git a/util/src/network/discovery.rs b/util/src/network/discovery.rs
index b67110538..d4f895702 100644
--- a/util/src/network/discovery.rs
+++ b/util/src/network/discovery.rs
@@ -28,7 +28,7 @@ use crypto::*;
 use rlp::*;
 use network::node_table::*;
 use network::error::NetworkError;
-use io::StreamToken;
+use io::{StreamToken, IoContext};
 
 use network::PROTOCOL_VERSION;
 
@@ -283,7 +283,7 @@ impl Discovery {
 		ret
 	}
 
-	pub fn writable(&mut self) {
+	pub fn writable<Message>(&mut self, io: &IoContext<Message>) where Message: Send + Sync + Clone {
 		while !self.send_queue.is_empty() {
 			let data = self.send_queue.pop_front().unwrap();
 			match self.udp_socket.send_to(&data.payload, &data.address) {
@@ -302,15 +302,17 @@ impl Discovery {
 				}
 			}
 		}
+		io.update_registration(self.token).unwrap_or_else(|e| debug!("Error updating discovery registration: {:?}", e));
 	}
 
 	fn send_to(&mut self, payload: Bytes, address: SocketAddr) {
 		self.send_queue.push_back(Datagramm { payload: payload, address: address });
 	}
 
-	pub fn readable(&mut self) -> Option<TableUpdates> {
+	pub fn readable<Message>(&mut self, io: &IoContext<Message>) -> Option<TableUpdates> where Message: Send + Sync + Clone {
 		let mut buf: [u8; MAX_DATAGRAM_SIZE] = unsafe { mem::uninitialized() };
-		match self.udp_socket.recv_from(&mut buf) {
+		let writable = !self.send_queue.is_empty();
+		let res = match self.udp_socket.recv_from(&mut buf) {
 			Ok(Some((len, address))) => self.on_packet(&buf[0..len], address).unwrap_or_else(|e| {
 				debug!("Error processing UDP packet: {:?}", e);
 				None
@@ -320,7 +322,12 @@ impl Discovery {
 				debug!("Error reading UPD socket: {:?}", e);
 				None
 			}
+		};
+		let new_writable = !self.send_queue.is_empty();
+		if writable != new_writable {
+			io.update_registration(self.token).unwrap_or_else(|e| debug!("Error updating discovery registration: {:?}", e));
 		}
+		res
 	}
 
 	fn on_packet(&mut self, packet: &[u8], from: SocketAddr) -> Result<Option<TableUpdates>, NetworkError> {
diff --git a/util/src/network/host.rs b/util/src/network/host.rs
index 03f37fa61..46185482f 100644
--- a/util/src/network/host.rs
+++ b/util/src/network/host.rs
@@ -236,8 +236,8 @@ impl<'s, Message> NetworkContext<'s, Message> where Message: Send + Sync + Clone
 	}
 
 	/// Send an IO message
-	pub fn message(&self, msg: Message) {
-		self.io.message(NetworkIoMessage::User(msg));
+	pub fn message(&self, msg: Message) -> Result<(), UtilError> {
+		self.io.message(NetworkIoMessage::User(msg))
 	}
 
 	/// Get an IoChannel.
@@ -248,12 +248,14 @@ impl<'s, Message> NetworkContext<'s, Message> where Message: Send + Sync + Clone
 	/// Disable current protocol capability for given peer. If no capabilities left peer gets disconnected.
 	pub fn disable_peer(&self, peer: PeerId) {
 		//TODO: remove capability, disconnect if no capabilities left
-		self.io.message(NetworkIoMessage::DisablePeer(peer));
+		self.io.message(NetworkIoMessage::DisablePeer(peer))
+			.unwrap_or_else(|e| warn!("Error sending network IO message: {:?}", e));
 	}
 
 	/// Disconnect peer. Reconnect can be attempted later.
 	pub fn disconnect_peer(&self, peer: PeerId) {
-		self.io.message(NetworkIoMessage::Disconnect(peer));
+		self.io.message(NetworkIoMessage::Disconnect(peer))
+			.unwrap_or_else(|e| warn!("Error sending network IO message: {:?}", e));
 	}
 
 	/// Check if the session is still active.
@@ -267,7 +269,7 @@ impl<'s, Message> NetworkContext<'s, Message> where Message: Send + Sync + Clone
 			token: token,
 			delay: ms,
 			protocol: self.protocol,
-		});
+		}).unwrap_or_else(|e| warn!("Error sending network IO message: {:?}", e));
 		Ok(())
 	}
 
@@ -714,7 +716,6 @@ impl<Message> Host<Message> where Message: Send + Sync + Clone {
 				debug!(target: "network", "Can't accept connection: {:?}", e);
 			}
 		}
-		io.update_registration(TCP_ACCEPT).expect("Error registering TCP listener");
 	}
 
 	fn session_writable(&self, token: StreamToken, io: &IoContext<NetworkIoMessage<Message>>) {
@@ -910,11 +911,10 @@ impl<Message> IoHandler<NetworkIoMessage<Message>> for Host<Message> where Messa
 		match stream {
 			FIRST_SESSION ... LAST_SESSION => self.session_readable(stream, io),
 			DISCOVERY => {
-				let node_changes = { self.discovery.lock().unwrap().as_mut().unwrap().readable() };
+				let node_changes = { self.discovery.lock().unwrap().as_mut().unwrap().readable(io) };
 				if let Some(node_changes) = node_changes {
 					self.update_nodes(io, node_changes);
 				}
-				io.update_registration(DISCOVERY).expect("Error updating discovery registration");
 			},
 			TCP_ACCEPT => self.accept(io),
 			_ => panic!("Received unknown readable token"),
@@ -928,8 +928,7 @@ impl<Message> IoHandler<NetworkIoMessage<Message>> for Host<Message> where Messa
 		match stream {
 			FIRST_SESSION ... LAST_SESSION => self.session_writable(stream, io),
 			DISCOVERY => {
-				self.discovery.lock().unwrap().as_mut().unwrap().writable();
-				io.update_registration(DISCOVERY).expect("Error updating discovery registration");
+				self.discovery.lock().unwrap().as_mut().unwrap().writable(io);
 			}
 			_ => panic!("Received unknown writable token"),
 		}
@@ -946,14 +945,14 @@ impl<Message> IoHandler<NetworkIoMessage<Message>> for Host<Message> where Messa
 			FIRST_SESSION ... LAST_SESSION => self.connection_timeout(token, io),
 			DISCOVERY_REFRESH => {
 				self.discovery.lock().unwrap().as_mut().unwrap().refresh();
-				io.update_registration(DISCOVERY).expect("Error updating discovery registration");
+				io.update_registration(DISCOVERY).unwrap_or_else(|e| debug!("Error updating discovery registration: {:?}", e));
 			},
 			DISCOVERY_ROUND => {
 				let node_changes = { self.discovery.lock().unwrap().as_mut().unwrap().round() };
 				if let Some(node_changes) = node_changes {
 					self.update_nodes(io, node_changes);
 				}
-				io.update_registration(DISCOVERY).expect("Error updating discovery registration");
+				io.update_registration(DISCOVERY).unwrap_or_else(|e| debug!("Error updating discovery registration: {:?}", e));
 			},
 			NODE_TABLE => {
 				trace!(target: "network", "Refreshing node table");
@@ -1004,7 +1003,7 @@ impl<Message> IoHandler<NetworkIoMessage<Message>> for Host<Message> where Messa
 					handler_token
 				};
 				self.timers.write().unwrap().insert(handler_token, ProtocolTimer { protocol: protocol, token: *token });
-				io.register_timer(handler_token, *delay).expect("Error registering timer");
+				io.register_timer(handler_token, *delay).unwrap_or_else(|e| debug!("Error registering timer {}: {:?}", token, e));
 			},
 			NetworkIoMessage::Disconnect(ref peer) => {
 				let session = { self.sessions.read().unwrap().get(*peer).cloned() };