Sounds like your computer's been hi-jacked by malware. I'd say it would be worth at least a try of downloading ad-aware (by lavasoft) and spybot search and destroy, and then running them one after the other and see what they report and if your problem is solved. They're both free.
Also, I recommend you download firefox from mozilla.org- it may be that you can still use another browser without problems in the meantime (but I would try and fix whatever is wrong).
If its a bad malware infestation, you might have to download those programs on anthother computer and then transfer them over. Good luck. For the record, I'm not a computer expert (sounds like your wife might be), but those are good steps to take, anyway, for all computer users- and it might work. Again, good luck.
Thanks, I downloaded Lavasoft and installed it. However, when I start the scan, I now get a message saying that my system will shut down in one minute, then it does, while the scan is going on. HOw can I stop the shutdown? Thanks.