Can’t change home page in IE7

Hi guys, i have a question regarding IE7 and its default homepage.
I think i have tried everything and anything on how to change homepage from MSN to say Google, but its changing back every time you restart IE.
I have triple checked IE7 settings and altered registry, and uninstalled spy ware software and disabled anti-virus just to see if its locking the default page in IE7 from being altered and nothing seemed to work so far.
the only thing i can do is add a web link in the property box in quick launch icon next to executable, that points me to that web site.
I’ running Sophos enterprise, is there a way i can change the setting without referring back to IE 6?
Thanks