newark
I think you may have one of the very stealthy viruses that is proliferating the internet.
I can't remember the name but it leaves a folder on the root of your c
drive called something like abc123 (sorry can't remember that name but it was a few weeks ago I stumbled over it) If my colleague remembers tomorrow I will post the actual name and the virus, but check your c
drive for a weird folder and if you find it google it then you should get the fix.
If this is not the case then try
SpybotSD which gets rid of stuff that Ad-Aware leaves behind.