External LCD malfunctioing. Is it my T42 graphics card?

[teepee]

I've had my T42 set up as a desktop replacement for 99% of the time the past 3 years or more. Runs through a port replicator to get the DVI port, to feed an external LCD. Early Januayr the external LCD wouldn't switch on. Had a flashing green light which indicated a failed board inside the monitor. So it was replaced, with a refurb.

The refurb worked fine for 2 weeks or so, but then started showing 'vibrating' vertical white and black (at least I think black) stripes where the screen should be black. It was intermittent. Over the past week the problem has become more common and sometimes I now get the whole screen (ie all colours) going white stripes.

If Iundock the T42 and just use the T42's built-in display, no problem.

So I've tried running VGA from the T42 to the display. Started off with a full screen of vibrating white lines but has now settled down and I've not seen any white striping for a good half hour, which is a good 25 mins longer than I was managing this morning via DVI/dock. It auto adjusted and so is running at low res, matching the T42 display, rather than the higher res of the monitor that I get with DVI.

So...

1) Can the graphics card or the port replicator cause the vibrating white line problem?
2) Does anyone have any opinion on which is most likely, faulty monitor or faulty card/replicator?
3) If it is the card/replicator, can they damage a monitor permanently (I don't want to buy a new LCD, hook it up and have my T42 damage it)?
4) If the problem is the T42 card is it easy to replace?
5) Could the higher res required for the external monitor be a factor?

I appreciate any advice

[Harryc]

Try hooking up another laptop or desktop to the LCD. Same problem?

[teepee]

Haven't got one at the moment, but that will be sorted early this week hopefully.