there's lots of reported bugs with xp stating that it registers the incorrect clock speed; but cpu-z should read the correct speed. As your cpu-z and windows are reading the same and your second attempt at over-clocking didn't have any effect; i'd think your best solution is gonna be a format.

win7 ftw... or be brave and go linux ^_^

yeah no other choice : P

oke today all of the sudden my cpu clock is back to 3.1 ; D