strange external monitor problem

[mikek]

Using external monitor with T60. Often hot dock/undock. All has worked well for months, since last few days when immediately after docking, the external monitor displays - as it should... then after about 5s goes black.

Cycling through FnF7 sometimes makes it work.. sometimes not. But what always does is just unplugging the monitor from back of the dock and plugging in again.

If boot up in dock, sometime OK, sometimes it will be fine until the windows blue log in screen appears (Xp, PC member of domain; same problem if domain available or not) - then it will blank after a few secs. Monitor believes there is still signal - ie it doesn't complain that there's no signal like it does when cycling through F7....

I've updated BIOS and video drivers, tried with and without presentation director.....

Any ideas what's going on?

[mikek]

Not surprised no one's answered.... it looks like I've got a dodgy monitor.... monitor substitution has proven it to be the monitor.