Next time you freak out about there being dust in your computer, do not attempt to take it apart because you will break it.
...this stems from me being a complete clean freak as far as my laptop is concerned. I take it apart regularly and clean the fan and all the other random bits and pieces. The only part I'd never done was the heatsink (the bit that cools the processor). In removing the heatsink, I managed to tear out the processor (which was not supposed to come out - it was locked into the motherboard with a switch that was accessible after the heatsink and cooling system was removed) because it was stuck to the heatsink with some heatsink paste (stuff meant to help cool everything down, not meant to stick).
Two hours later, I had a dead computer and a processor which would not go back into place because half of its pins were bent (due to aforementioned wrenching). I managed to eventually get them straightened out and separate the heatsink from the processor in order to put everything back together, but my poor laptop still wouldn't work :( I prodded it a bit and realised I'd put the fan back on upside down. Correcting this meant I had a working laptop once more.
Needless to say, I got laughed at by others who know far more about this sort of thing than I do. >.< ...I believe I have learned my lesson.
(Though having said that, I was very slightly hoping my computer had permanently died so I could get a new one :P )