WARNING! big image below! and read everything before trying what you have read! then read again! digitalmouse is not resposible if you screw up your monitor/computer/video-card!

find the vertical and horizontal refresh rates for your video card (either in the manual or on the net). Make sure to set those in the System Settings->Display->Advanced tab:



Click on the "configure" button, and you will see the Monitor settings window appear. Find the model number for your monitor from the list on the left hand side - if it's there, it should fill in the refresh rate detail automatically.

If not, you have three choices:
1) find a monitor with the same refresh rates (often a similar model may have similar specs), or
2) choose the "Generic" triangle (which expands a list of generic monitor configurations) from the top of the list, and pick a configuration that has the highest resolution your monitor can handle and the has the correct Horizontal rate (the "@ blah" number), or (and this is probably the one you'll use since it works most often)
3) click on the "Generic" title in the list (not the triangle) then enter the model name, then Horizontal and Vertical ranges, as given by your monitors manual or website.
(I guess you could also try a fourth option and click on "probe" to see what RH can determine automatically for the monitor - in fact, try probing (then follow the directions below) before trying step 3)

Click "OK", close the Display Settings window, then logout to restart Xwindows (carefully read the notice that appears after closing the windows, explaining what to do).

Assuming you didn't screw up and you don't here any odd noises from the back of the monitor, log back into your machine, go to the Display settings window again, and try uping your resolution (I would suggest something small like 1024x768 at first).

Good Luck!