Monitor Says Over Range


I have a mac. but my monitor is a PC monitor. I made the resolution higher and my screen went black and then said "over range," because I guess the monitor couldn't handle that high of a resolution. I have done this before, and someone helped me restart it and get back my old settings, but I don't remember how I did it. Can you help me? my technical level is NOT high.
See if the screen comes up in Safe boot. Startup you Mac while holding down the Shift Key. You will come to a log in screen the has the red letters: Safe Boot . Log in then when OS X comes up, open System Preferences and change the Preference back to your original setting. Then reboot, Good Luck.
I have had this same problem. I rebooted my mac mini OS10.4 (with Sceptre monitor) in safe boot and returned to the proper settings for the resolution. However, the next time I went to log in it happened again. How can I stop this from continuing to happen?