Have you tried going back to a restore point dated before your problems began and see whether your PC runs normally?
Secondly have you tried running comodo and avira with your PC in safe mode to see if anything shows up?
It does seem odd that you cannot access the internet though on two separate PCs, so possibly not a virus on one of them. Just a thought, are you using the same ethernet cable on the laptop as the PCs? If not it might be the cable that is at fault.