Go to this page and download SpywareGuard. What it will do for you is when an attempt is made to change your homepage a box will come up saying it has been changed from ................. to .............. would you like to keep the new value or restore the old value. Normally you will want to restore the old value. The only time you will want to keep the new value is when you set up SpywareGuard.
http://www.nrtco.net/~polarbear/links.html