Different L90D+ problem

Set up a brand new L90d+ on a ATI X700 set up last night. I did it in a drunken haze after coming back from a party, so when it wasnt working right I thought I had probably messed it up. Today in a soberer haze I see the fault doesnt seem to be mine.

using the VGA analog connection all is well.

using the DVI causes the screen to go blank when logging into a use profile with XP pro. It will boot and i'll see the splash screen and I will enter windows using DVI. Once i select a user profile to log into, however, the screen goes out. I don't get the new signal message, i just get the orange standby light for infinity. Sometimes this is instantaneous when selecting a use profile, other times it happens after a few seconds of use. I think all is well, then bam, no screen.

Help! I bought this monitor for my sister and she lives too far away for this to be a problem, i dont want to drive to long island every time her screen disapears, and I refuse to use the VGA connection for good, her card has DVI, the monitor has DVI, i want to use DVI! plz help, the tech support site for Hyundai is non existant

<font color=orange>System: Tandy 386
12Mhz of pure <b>power</b></font color=orange>