Hello and Welcome to Windows7forums..
I want to help you but I'm going to need some more information..
Did you do a Clean Install of the Win 7 RC or an Upgrade install? Is this the first time this has happened or did it happen previously? Have you recently installed or upgraded any drivers? Which version of Windows 7 Rc are you using (32-bit or 64-bit?).. If you could answer these questions for me I can get a better idea of what has happened..
Also, have you tried using 'System Restore' to restore your pc to state prior to this happening?