Radeon 9500 to TFT problem (DVI-I > DVI-D related?)

I have a Sapphire Radeon Pro 9500. I recently purchased an Acer AL1731
TFT display and connected it to the card using the DVI cable supplied
with the TFT.

This used to work - crystal-clear picture, signal detection on
power-on - until I updated drivers for another system component (USB
MIDI interface - no obvious connection, but that's the only part of
the system I changed).

Now the DVI connection won't work anymore, only an analog D-sub
connection. When the DVI cable is connected, the signal from the video
card is not detected, and the display goes to standby.

On startup, the TFT shows the inputs that it is currently scanning.
The odd thing is that while checking Analog RGB and S-Video inputs
takes circa a second, the "Digital RGB" is only scanned very shortly
(and not recognized) as soon as a cable is connected.

The Radeon 9500 has a DVI-I connector, while the TFT has a DVD-D
connector. Could this be the source of the problem? How can I get the
DVI connection to work again?