Browser Hijacked by malwareurlblock.com/block.php Personal Antivirus

My IE 7.0 has been hijacked by Personal Antivirus which always displays a warning message about a virus and sends me to thei page to vuy software. it is connected to malwareurlblock.com/block.php

 

Norton Antivirus did notdetect it and does not find it when I perfrom the full scan. Any idea how to remove it?

 

I remove all the software and registry entries referencing "personal AV" but it is still there.

Thanks,