2. Select "Generic Multisync"
 

a. This may not be the best, but it should give reasonable results

b. The program will probe the monitor and select the best resolution and color depth automatically.
 

a. Select reasonable values for resolution and vertical sync from the list

b. Select the closest vertical sync range but do not exceed the upper or lower limits of the monitor. Physical damage may result! Check the manual that comes with the monitor.

a. (Ctrl-Alt-Backspace) should kill the X-session

b. (Ctrl-Alt-Delete) should reboot the system
 

note: neither of these will work, see next step

3. Cause: You probably have a Diamond Viper 330 or similar card with the nVidia (aka Riva128) chipset. This is a video card IRQ conflict, generally with the ethernet or SCSI adapter. To remedy, physically move cards around in the system. This is a bug in the server, which hopefully will be fixed in the next releases of XFree86.