Every now and then my computer screen starts flashing multitudes of colours - sometimes squares, sometimes vertical lines. When this happens the only way I can turn the computer off is to hold the power switch in for several seconds - the re-set button has no effect. Can anyone offer a bit of advice please?
Hmm, as you obviously are not familiar with the inside of a computer case, you should probably leave it to the experts by taking it to your local friendly PC repair shop. Not a cheap business though, most shops charge about £25-£35 an hour just for the privilege of looking at the PC.