Lost DVI signal

[Ronin13]

I just finished building a new PC with the following componenets:

ASUS P4C800-E Deluxe
P4c 3.0
2x512 Kingston PC3200 RAM
Visiontek GeForce4 Ti 4400
Samsung SP80 160GB, 8MB buffer, SATA drive
Plextor PX 712A
In an Antec SLK 2650 BQE case
On a Samsung 173t LCD monitor

When I first booted up the system, I used the DVI port and it worked as it should with the basic graphics drivers from WinXP.

After I updated to the latest WHQL Forceware drivers for the GeForce, the monitor remains black on the DVI signal, but the analog signal is fine.

I also tried running an older Detonator driver, with the same result.

What am I doing wrong?

 

[Ronin13]

UPDATE:

I tried going back to an earlier restore point, just after the fresh Windows install where the DVI signal initially worked. No change; the analog feed works fine - the DVI shows a black screen.

I also tried hooking the screen up to another PC, which has a Radeon 9800 Pro, with the exactly same results; the analog feed works fine - the DVI shows a black screen.

This indicates that the problem is with the monitor, but how do I go about 'reviving' the DVI signal?

(Some more details: The Samsung 173T has a 'Source' button - the second from the left - that lets you shift between the VGA and DVI signals, as I undertand it. With both cables connected to a graphichs card, the analog signal works fine, but when I press the 'Source' button the screen turns black for a few seconds before changing back to the analog feed. If I boot with only the DVI cable connected I just get a black screen.)