When I turn the computer on, everything is fine, and I can log into my account. But once I do log into my account, the screen stutters a LOT, and it eventually crashes. Background info: right before this happened, I installed a new video card on my computer, the MSI ATI Radeon HD6450, since I was told it would work on my computer, an HP Compaq 8100 Elite Small Form Factor. I replaced the bracket on the video card with the smaller one, put the Vega bracket on top, connected the video card to the black express bridge in the computer and then connected the VGA and the DVI cables to my monitor. If I use the VGA output, it won't load, and if I use the DVI output, it lets me log in but then it stutters and crashes. But it didn't crash at first. I used the disc that came with the video card to install the drivers. Then it told me to restart the computer, so I did, but now I can't see anything or it'll stutter and repeatedly crash. Am I doing something wrong? I made sure that the video card was in place completely.