RedHat 9.0 monitor frequency over range
i installed redhat 9 for the first time, (also first time with linux OS).
it installed perfectly fine, on boot up i had a similar problem to yours, if not the same prob.
The problem for was the screen resolution. My monitor is quite new, but the resolution of 1024 by 768 is too high for it. Not sure why, i thought it would work.
At this time of the monitor complaining about frequency, it was at the login screen, but the screen display was totally black.
When the error was showing, i lowered the screen resolution from 1024 by 768 to 800 x 600.
Do this by holding CTRL + ALT + - (minus key).
If this works, then you wont be able to use 1024 by 768.
I'm using 800 by 600, dont like it much but its the highest i can go.
If this works, then you can always change settings in redhat.
Hope this helps.