Hi Mike, I've scanned with AVG & Malwarebytes & SUPERAntiSpyware, although they found some threats, but cleaning them does not solve the problem.
And now I have another issue. I just realize I cannot boot into Safe Mode under Win XP.
During boot up, the F8 option only available for the Win 7 and not the Win XP.
I tried to boot into Safe Mode under Win 7, log on as Admin, and try to modify the Start Menu->All Programs entries for the Win XP, and it's not allowed too.