Yes, viruses commonly cause that - they take over your address book.

http://free.grisoft.com/

Carole, please download the above (free version on the left side of the page) and have it scan at the same time every day, ok? If you have trouble with the Task Scheduler, ask someone to help you.

http://www.safer-networking.org/en/

In the upper right-hand area of the above link is Spybot Search and Destroy 1.5.1 It's also free. Download it and run it at least once a week.

I use both of these, and they keep my 'pooter safe and clean.

Happy New Year!