hi detroit... an online virus scan? haven't heard of that...
Haven't heard of an online virus scan? Housecall from trend micro is a very useful tool. Its not a real time scan as you have to access the site, but it offers a great second opinion to your resident AV software .... or as a first opinion in the case your AV software doesn't detect. I like HOUSECALL because it uses the same definitions as PCillin, which won cnet's editor's choice awared for AV software in 2004. You can check it out
HERE.. However, now-a-days, almost all the major players in AV software offer an online scanning tool.
Please don't dismiss spyware as the culprit either. More insight to the nature of the problem could be gained if you downloaded the latest copy of HijackThis and posted an HJT log. HijackThis shows a list of running processes, start-ups, BHO's, and downloaded active X controls which is helpful in sorting out software related problems. The drawback to HijackThis is it takes considerable knowledge and skill to use it correctly so its not the tool for most.
I'm hesitent to recommend system restore unless other things are tried first. Yes, its a very useful tool .... but in the case of viruses and spyware, often times a copy of the infection is stored in the system volume too. If it comes down to a format/reinstall to fix this system, you're better off using Norton Ghost right after you've got everything installed. Its a whole lot quicker to use a ghost image of your fresh install than to format/reinstall every time your system acts up. Sure, you can create a restore point with system restore that would do the same thing. However, after a while, old restore points are purged to make room for your new ones and in a short time you won't be able to use that fresh install restore point you took the time to make.
P.S. Bad/corrupt drivers can also cause the symptoms you've described. Event viewer might give you extra insight as to what is going on. Keep posting as one of us here should eventually help you get things all sorted out.