No external display yet internal display is fine

I have a problem with my laptop not displaying to any external display
monitor. The internal display fortunately is fine.


The external monitor is getting a signal from the vga port as it says
"cannot display this video mode" on one display or on another it does it says
the signal is out of scan range with scan at 300Hz. Sometimes that monitor
shows the display but garbled as not in sync.

These external monitors work fine for another computer and so the monitors
are ok.

Everything was fine for the ext monitor on my laptop too about a month ago.
I don't project to ext monitors very often but did a presentation then and
all was fine. So something happened in last month.

I have updated video driver. I download a specific monitor driver for one
of the monitors and neither helped. I updated BIOS in laptop and again no
avail.
Seems to me the video adapter is either not functioning (hardware wise) or
some setting is not right. Since the internal display is fine and I get a
signal to the ext monitor and sometimes it is garbled (not in sync) I would
think it is a config issue.
Boy I have looked all over for guidance on this issue and setting configs.
Saw stuff for linux but not on windows xp.

Specifics of my laptop

Toshiba Tecra M1
Windows XP Professional
Display Adapter: Trident Video Accelerator Cyber XP-4 v6.4823-104

any guidance is greatly appreciated. Beyond the specifics of this laptop,
the issue is what might of happened to stop ext display even though internal
display is fine
thanks
walto