Got a strange one here...

Desktop ran fine on saturday but turning it on this morning and it'll boot up in the normal way, and all looks fine yet wont load anything? no drivers have been loaded. firefox wont load the internet????

Tried to run combofix but flashes up then shuts off? tried going into safemode but its exactly the same. Also noticed in task manager that it loads the same processes in normal mode as per start up mode?

Any ideas? bloody stumped here as it comes up with no error messages AT ALL!?!?!?!