Lisa,

I do NOT think it is a worm or virus - but a so called hijacker - as you can't update your ad aware - I would suggest:

Please go to http://www.spywareinfo.com/~merijn/downloads.html, and download 'Hijack This!'.
Unzip, doubleclick HijackThis.exe, and hit "Scan".

When the scan is finished, the "Scan" button will change into a "Save Log" button.
Press that, save the log as a .txt file, and copy and paste its contents into your next post.

Most of what it lists will be harmless, so do not fix anything yet.

Best would be to copy\paste your HJT log and go to Wilders.Org. as the other ones are having huge backlogs.

http://www.wilderssecurity.com/ - you have to register to post your HJT log !!

then look for: Browser Hijacks and Spyware Problems

adware, spyware & hijack cleaning - http://www.wilderssecurity.com/forumdisplay.php?f=26

Good Luck !