This week I had a revelation: My computer was switched at birth, and got put into the wrong box at the factory. These things happen. It's actually a piss-poor vacuum cleaner that puts on a major bullshit, smoke and mirrors act to divert attention from the fact that it's too weak to do any useful cleaning. So sly an act in fact, that I never even thought about my »computer« in terms of cleaning power until now.
About all it can manage to do is slowly clog itself with lint--and when I went to change the bag, it didn't even have one! Boy, did quality control snooze on that one or what? But once I finally got it cleaned out, a few crackling passes with one of those fluffy dusters that you twirl to generate lint-attracting static magically grabbed up every last particle of schmutz from the circuits and suchlike. It seems to have done it a world of good too, because the next time I went to use it, there was a lot less of the BS and the smoke and mirrors!
What with the quirks of automated mass production, it's worth a quick look inside your computer to see if this may have happened to you. If it's full of dust, that means they slipped you a vacuum in a computer box too, and one that snuck by without a bag installed at that. Just do what I did with the static wand thingy, and I think you'll like the results, although next time I'd probably back everything up first.