Screen Flashing And Freezing

i recently had to reinstall 7, because the computer kept crashing in the middle of the simplest things. say, i'd be reading a wikipedia article, or watching a Internet video, or playing a game, and the screen would all of the sudden start flashing for a few seconds, then it would just go black (70% of the time.) on occasion, it wouldn't go black, but instead becomes the color of the most prevalent color on the screen. ex: i was playing a game, and took a look at the map, which was mostly yellow. at that moment the screen would become yellow and freeze, not letting me move my mouse or ctrl+alt+del. sometimes a blue crash screen would appear, sometimes it would just restart on its own.so, anyway, i realize reinstalling windows has little to do with the above problem, but i was hoping it would fix it, and also i needed a new start, since my organizational skills were pretty bad before. once reinstalled, i had updated almost everything possible, via windows update, or manually.at first, i thought my wishes were fulfilled, because my pc was running faster and more smoothly than ever before. (i did have a little hiccup with sound card, but that's behind me now.) but, no. the black screen happened again today. that was such a low blow i wanted to jump off the balcony... i decided that the only thing i haven't updated was the bios, and, true, it was last updated in august 2010, 3 months before i got this pc. that hasn't helped one bit - screen's still flashing and freezing.

also, i've just noticed that after a few flashes the computer doesn't freeze at first, but the mouse pointer either disappears altogether or becomes thin vertical dotted line. but it still freezes after a few minutes. that's something new, but not an improvement. hopefully that helps you.[code] a quick flash or two, mouse pointer becomes a dotted line, and screen goes white (doesn't happen a lot, but has before) after 1-2 minutes. i was running 16-bit true color this time, but apparently that makes no difference.