I have a problem configuring my X server on my friend's computer. I was able to boot from the knoppix cd but X server won't come up. It shows me

Signal Error
HF: 62.5 KHz
VF: 75.9 Hz

This is the monitor control error that comes up and the screen goes blank. But I know that X server is running normally and its just that monitor frequency is not recognized properly or so. I have booted with many cheat codes like 'nodcc' , 'fb1024x768" etc. Nothing worked out. Finally, I booted with 'screen 800x600' and the X server is up with 800x 600 resolution. I installed knoppix on to the harddrive and it boots with the same resolution. Is there anyway that I can increase the resolution and still give the monitor the signal with correct frequency. Can anyone help me out??

Thank you.
Sanjay.