You might try this:
Start > Run > ( input ) - gpedit.msc > Enter > User Configuration > Windows Settings > URLs > ( right click ) - Important URLs > ( select ) Properties > ( tick ) Customize Home Page URL > ( input ) - Home Page URL > OK
I'd do it right after you clean it out.
If this is a trojan then try running
The Cleaner .
Free for 30 days - update definitions.
Bill