Shovel attack
I once got a deal on a PC that had been attacked by the owner's neighbour ... with a shovel.
The (at the time impressive) 19" CRT display had a couple of nice gashes in the top of the casing, but still worked. The base unit was a little worse for wear but I transferred all the components into a new case and it worked fine. The hard drive *did* have a few bad sectors marked, but it didn't deteriorate in the time that followed.
I never did find out what made the neighbour so angry, and why he decided to take out his anger on a poor, helpless PC with a shovel, of all things.