I've had problems with my K50 that appear to have rectified themselves; both my memory cards were giving intermittent errors. I updated to the latest firmware, but that didn't fix it. Taking it to a camera shop to show them the problem did, though! It has worked perfectly from the moment I put it in the tech's hands until now. She didn't do anything to fix it, it just refused to perform it's behaviour for her.
The problem isn't happening anymore anyways, so for now I'm going to assume there was some debris in the memory card slot that was causing the problem.
A fellow student in my local photo class also had a K50 with problems. His had to go back to Pentax for repairs; it was locking up and the electronic menu system was - for lack of a better term - wonky.
With the only two K50's I've personally laid hands on both having weird issues, I'm thinking maybe the K50 build quality is somewhat lacking. I love the feature set with the camera, but if it doesn't work when you want to use it - well - the features don't much matter, do they?