Hello. I'm new to this board. I have a pretty mediocre knowledge of computers.. No programming or anything, but a pretty average knowledge. Anyway, I have a Dell Dimension 4500, and I used to use it for editing independent films. I know it's not much of a system, but it's worked in the past, and I have an extra 250gig hard drive. My problem is, for quite a while now I haven't been able to play video. Every time I try to open a video file such as an avi, mpeg, wmv, mov, etc. on windows media player, winamp, realplayer, what have you... My screen starts to flicker on and off, sometimes it will stay off for a few seconds, and come back, but unless i stop the video from playing it eventually shuts off completely. It doesn't seem that the computer is turning off, but it's like it goes into sleep mode and i can't get it back. The flickering also happens when trying to do things like view those 360 degree pictures on the internet, or even when I open up certain applications. The strange thing is, I can't upload video via Firewire without it freezing and flickering, but when I import a file into my video editing program (Sony Vegas), I can watch the video without that happening. So far, that's the only application i've found that I can do that in. Does anybody have any idea what this could be? Do I not have enough RAM? Is it a video card problem? motherboard? am I overheating? If anyone has any feedback, please help me out. I need to be able to upload, edit, and play video again, as I have a wedding video coming up. Thanks again. By the way, the video card in my system is not the original. Something messed up with the orginal, and I replaced it with a NVIDIA GeForce FX 5200. All the rest of my system specs are in my profile. Thank you anyone for any help you can provide.