I got a 5870 GPU and I would like to dual monitor so I connect the first monitor DVI to DVI then when i got to setup the other which is HDMI to HDMI my DVI screen starts flashing and then the GPU driver stop responding and if I leave the PC there for 30seconds or more the PC restarts. Its really weird.
The DVI monitor is a HP L1940T ( 1280 x 1024 )
The HDMI monitor is a TFTV4839DT ( 1440 x 900 )
Its been a while since i did any of that from what i remember its all about getting it set up in the drivers properly. One needs to be primary and the other secondary then you get options to extend or clone the screens. it could be that the two are clashing.
I looked up this video that runs through a W7 install and it would seem like both monitors should be connected at atart up which could also be the issue i guess.