Pressing F8 does not bring up "Repair your computer"0

Hello all,

I have had a few problems with my Vostro 1500. After backing up the files i wanted i thought i could do a straight forward dell factory restore; but pressing
F8 does not give the option to repair your computer. i have done this in the past without problems so was a little concerned. i decided to reinstall vista manually hoping that this would bring back the option to repair your computer but no such luck. My question is, is there a way to get that option back in the F8 menu. the dell recovery drive is still there but i don't how to activate it again.

thanks in advance.

Phil