Philips 105s monitor blanks in dos full screen

[mike_bio]

Hi to all.

I own a Philips 105s (15inch/CM2300) monitor. After a power failure last week, the monitor just refuses to work in DOS full-screen mode, while it works just fine in Windows.

The problem goes like this. I turn on the PC and the monitor, and nothing is shown, while I can hear the whole booting process. The computer enters windows and still nothing is shown. When (while in Windows) I turn off and on the monitor, everything is shown!
If I try to boot directly in DOS the monitor never shows anything (even if I turn it off and on).

The same problem comes up when (in Dos prompt) I try to switch from full-screen to window. (the opposite works just fine!).

When the monitor is blank, if i disconnect it and connect another monitor, i can see everything ok.

I have reached the conclusion that the monitor is to blame because I tried the monitor with two different systems and it acted just the same.

What confuses me the most is that the monitor does not work in dos (it doesn't even show the first bios screen) ut it works in Win!

The two systems I tried the monitor are (both with win98):
a)Intel p166, 40MB RAM, S3 Trio 64v2-dx/gx(775/785), Soyo 5vx mobo
b)Intel pii MMX, 128RAM, Video card:Intel740 Win9x pv2.1-980727.

Any suggestions?