Whenever I turn on my comp, flickering colorful lines has started to apear on my screen, and when I enter a game which involves 3d it goes even more bananas! Can someone tell me whats wrong with my comp??.. Im not on LSD...
It could be a video card issue, meaning it could going out on you and you may need to replace it. I had something similar like that many years ago with my old geforce 4. If you have an extra video card, try that out and see if it does the same thing.
Yup, it does sound like a video card issue to me too. However, before you swap the card out, you ought to try getting a newer video driver, or reverting back to an old one.
Also, check the tempurature of the card to make sure that it's not getting too hot.
It does indeed sound video related.
On that note, be sure to check the connections of your video cable on both the monitor and the back of your pc. If you have another cable to use, try it as well to rule that out as being the problem.
Try updateing your drivers to the latest version. In addition to all the suggestions above you could also try reseating the card (pulling it out of the slot, then putting it back it) if your comfortable opening up your computer.
If it happens as soon as you turn on the computer, as right after you hit the power button, i would rule out overheating as the card would not have a chance to warm up to temperature that would start causing errors.
What video card do you have?