PC with S3 OnBoard video card, LG monitor, Win98SE.
On startup it shows:
Out of Frequency
HF 27.8 kHz
VF 62.0 Hz
HF 30-71 kHz
VF 50-160 Hz
Changing monitor to another LG didn't change anything, but using one older ADI monitor worked, initially.
So, I installed some printer driver, changed BIOS (USB was not enabled) and after few restarts I'm getting "Out of Frequency" again. This time second monitor doesn't show anything.