Peter,

Unfortunately there seems to be no Silver bullet for what you are asking. I have 4 computers in my computer room and the one has exactly what you are talking about. Same thing exactly but on a Windows 2000 Professional OS

I have tried and McAfee and AdAware both to no avail. I had a similar experience on both 2000 and XP Professional and in both cases I ended up re-installing the operating system.

The main thing is to get off ALL CRITICAL information off the computer to another computer or DVD or CD.

Make sure you know where all your driver disks are and your Windows re-installation disk. If you own a dell all of these drivers are online for your machine.  Re-installation is not quite as daunting as in the old days.

Good luck and let me know if you find the silver bullett

--Pat