2000+ unlocked and a7n8x (nForce2)

hello !
I tried to unlock a palomino 2000+.I verified my work with a scanner.The stripes seem to be clearly separated(i isolated the pits with non silver thermal paste and locked with silver one).But i can't change the multiplier !
When i try another setting,upper or lower,this message appears : "WARNING ! The CPU is over speed !" or something like this,and it doesn't pass post.
This sort of things happens when the processor is not correctly unlocked.But,due to the mainboard,i'm thinking about a BIOS matter too.As i got a recent version of it (1.001g),i just wanted to know if someone got an idea about this.
PS:i purchased a palomino because i wanted to wait for a lower price for tbred or barton.I expected this processor to run at 166 FSB (overclocked,that's my problem !),but as i can't change the multiplier ...
if i can avoid unlocking it again !