If you have a machine that has had it's WGA validation mess up. You need to reset it, check for any WGA updates and then retest the WGA validation. Here's a script to do it.

Code:
@ECHO OFF

IF EXIST "%ALLUSERSPROFILE%\Application Data\Windows Genuine Advantage\data\data.dat" (

ECHO Deleting data.dat
attrib -R "%ALLUSERSPROFILE%\Application Data\Windows Genuine Advantage\data\data.dat"
DEL "%ALLUSERSPROFILE%\Application Data\Windows Genuine Advantage\data\data.dat"

)

IF NOT EXIST %WINDIR%\system32\WGATray.exe (GOTO END)

ECHO WGA Validation in progress. Please wait...
WGATray.exe /b

:END

ECHO Done