As above. Disconnect from the mains, remove all the connections from the back of the PC, remember where they go, especially the mains 'kettle' type lead. Set the PC in somewhere well lit and carefully remove the case side. Use a new painter's brush to gently brush off excess dust while holding the end of a vacuum cleaner nozzle to extract the dust that's dislodged. Take your time doing it and make sure you don't dislodge a connection anywhere inside that PC. Give a thorough check that all connections are sound then replace the case side and reconnect. If you're worried about 'earthing' then simply put both hands on any tap in the house so no need for those fancy bracelets.
Hi thanks for the advice so far. I have done asinstructed by rdave13 and so far I have been online for about 5 mins without being kicked off :o) I have moved the pc to the living room for the past few months so it would of collected a lot of dust in that time so hopefully that is the only problem and it is now fixed. Thanks again.
OK I spoke to soon. The pc is still rebooting so could it be a virus that is causing the problem??? I do have something on my system at the moment that I am struggling to get rid of called Vendrow A. Could that be the cause?