Help!! Cannot change Home Page

I had to do a full reinstall of my system. Now I can't change my Home
Page. I tried everything:
1. Ran virus/trojan/spyware checks (it doesn't appear to be the
product of a trojan as it remains on gateway.com)
2. Disabled/removed all anti-virus, anti-spyware and firewall programs
as well as toolbars.
3. Disabled everything but the most crucial startup items
4. Relaxed security for Active X components
5. Removed and reinstalled IE Windows component

Then, I tried a few registry changes (based on some Microsoft
literature), but to no avail.

I then downloaded StartPage Guard. I tried to change the home page
with that and I got the following error - RegSetValueEX failed with:
5.


Anyone have any ideas???

Thanks.