Rarely any props on my map, and it crashes all the time when I open prop C all the time.Your own map you have open right now can contain enough props that together with the library they crash hammer. Try to close your map and load library then.
When I open Prop library C, hammer crashes. That's it, that's really it. I don't know why.I don't understand what your problem is. Would you mind providing a longer description?
I've tried once and it solved nothing. I'll try again though.Does it give an error or does it just close without anything to say as to why it closed?
You can always try checking TF2's files via Steam->right-click Team Fortress 2 in the game library on the left->Properties->Local Files->Verify integrity of game cache. This will replace any corrupt/missing files that could be there due to Steam updating TF2 while Hammer was open or something similar.
Make sure Hammer (and TF2 for that matter) is closed when doing that. Otherwise nothing will be changed.I've tried once and it solved nothing. I'll try again though.