Thanks,
Firewalls are not the problem. On our setup we have three plus three anti virus programs, two servers, one Linux box dedicated to all things email and internet. Incidently we would log 100's of virus infected emails a day and we are only a small company.
Actually I tried what you suggested changing the home page through tools, options. Did the trick for a while but it came back. Looks as if Ad Aware and SpyBot finally erased the offending passthrough when I booted up my PC in safe mode.
I got hooked when I inadvertently opened a spam email instead of deleting it.