Happens to me too!! My Aero suddenly stopped today saying my Geninue isn't valid. I was able to go thru validation pages for software downloads before. Problem starts today.
I try to retract what I've done to Vista (from recent to old): I installed .NET Framework v1.1 (this crazy ClickArt 1,200,000 software wouldn't use my .NET Framework v3.0 and refuse to install until I install v1.1), WIOCOMM Bluetooth software installation, fatal BSOD (just once.. didnt run chkdsk.. maybe I should have).
Now, my Vista is not geninue...