My screen goes black frequently for a second, and often the screen freezes. Nothing I do (escape key, C+Alt+Delete), has any effect. Oops! there it goes again! (Rushing now before it freezes!) Then I must reset. I appear to have several out of date drivers; all devices report working properly; also, the UPS cannot be activated. Windows troubleshooter won't work; have scanned for viruses, spyware; All windows updates are current, but am unable to download drivers. Videos will no longer work with Quick Time (recently uninstalled and reinstalled). What's up, and what will go wrong next? Should I bring computer to the repair shop? Thanks for any help. Multimoe.

It sounds like you need to totally re-install your OS. Use Killdisk (It's FREE)
KILLDISK
to get rid of any nasties that will survive and FDisk or do an FDisk and re-install your OS again from scratch. After doing this and before connecting to the Internet for the usual Windows update install an Anti Virus first.