Apple Mac startup issue - monitor hertz too high to view on monitor

Ok, had an issue yestersay - old version of MAC OSX wouldn't startup on our new ViewSonic monitor due to too high hz resolution (90hz x 75hz), after a few reboots trying to telnet in to change the config startup file found that if you startup in SAFE mode then it will get past it so you can then change the settings to 60hz for the monitor graphic display in System Preferences.

To statup in safemode:

To start up into Safe Mode (to Safe Boot), do this:

1. Be sure your Mac is shut down.
2. Press the power button.
3. Immediately after you hear the startup tone, hold the Shift key. The Shift key should be held as soon as possible after the startup tone, but not before the tone.
4. Release the Shift key when you see the gray Apple icon and the progress indicator (looks like a spinning gear).

During startup in Mac OS X v10.4 or later, you will see "Safe Boot" on the login window, which appears even if you normally log in automatically. During startup in Mac OS X v10.2 through v10.3.9, you will see "Safe Boot" on the Mac OS X startup screen.
To leave Safe Mode, restart the computer normally, without holding any keys during startup.