I have NO IDEA what the hell this weird problem is. I have a PC in my room, but its essentially just a server for me to stream to my PS3, and download things with. However, Its a fairly solid computer, as it was donated by someone who recently bought a new one. I cant recall the processor atm, but it is 64bit Intel based. 2GB of Ram, 520watt power supply, running on Windows 7 Home Premium. Anyway, Since I was using the onboard video, as i wasnt playing games, it was fine, but today my dad gave me his old Geforce 9400GT as he updated his card and had no need for it aswell, i thought I might as well pop it in.

I install the hardware, download the drivers, ect and everything is fine. I bootup steam, Run Portal 2, and it runs fine. Well It has 2 DVI outputs on it, so I decide to plug it into my TV. Its not a LCD, but it does have HDMI on it, so I can atleast have dual monitor, so I can play a handful of my games on my TV rather than the small 17inch LCD i have on the window sill (like I said, It was supposed to only be a server and a brdige for files between the internet and my PS3). I plug it in, I see the image on the TV, adject resolution settings and its all fine, and then I try to boot up steam.

AND BAM. Nothing is working now. The whole thing essentailly froze up. Forced a Blue Screen and restarted. I should mention that other than steam, utorrent and an mkv conversion program, nothing else is installed on this computer, and its not even used for internet browsing, so i couldnt have picked up something from somewhere.

Upon restarting... it doesnt. Windows loads technicly, but just hangs after desktop icons pop up. I even unplug the second monitor and nothing. Blue Screen forces again. I boot in safe mode, and do a system restore. nothing. I finally pulled the card and did another safe mode boot and system restore, and it works again.

However, I would like to know WHY this is happening. I want to use my monitor as a dual display. How is only running something as a second monitor COMPLETELY FUCKING UP my entire system to where it wont even reboot correctly? Is there a setting I need changed? Is the card broken? Is it not getting enough power? Is it incompatible with something?

I reinstalled the drivers, and the hardware to try it again. While Ive yet to get a lue screen, It has just hung up completely forcing me to just restart the whole computer. Like I said, things were working fine, until I plugged in the second monitor and tried to run steam. not even a game from steam, but the actual steam.exe itself.

Can someone help me with my problem, or atleast explain why its happening?