Grrrr!! I can't install!!! (Monitor + ati issue)

[nimes]

hi, i tried install intrepid but after usplash are'nt start gnome desktop. monitor sometimes on/off, finally off.

my system spec:
-ati 3870 grapihic card (dvi socket)
-Asus 17 inch lcd monitor
-intel motherboard


not: i also tried safe mode installation, but no success

i gone crazy...

[police512]

perhaps its the cd test the cd for defects. or burn it with a lower speed

[nimes]

i also try usb installation. same results.
usb installation works on my laptop