Sometimes gamers are the worst. In the search for FPS they'll disable services, tweak registry values, overclock to the breach, buy hardware that hardly anyone supports, and/or install all manner of 3rd party "fixes" and "optmizers".
Months pass and they forget what they did. A new game comes out and (unsurprisingly to everyone but them) it crashes.
I'd say about 25% of the cases I read in the tech support forum are probably related to something gamers did to their own PCs.