my dimension 3000 problem.

hi, i just joined this forum with the hope that someone can tell me whats wrong with my pc.

ok, i no longer get the dell screen on start up i just get-
81k / 155hz
frequency is out of range

its the standard crt monitor i got with the comp a e772p or something.
i tried formatting a spare hard disc and the screen did the same during xp installation.

i've tried booting in safe mode to change resolution etc but guess what? yup it does it again

i've litrally spent ALL day trying to fix this problem with absolutely no joy.
i rang dell but got fed up with getting passed to and from hardware and software support.

i've tried another monitor too......IT JUST KEEPS HAPPENING!

help in any form would be much appreciated, thanks joanna