quota

disk space and other limits

in the terminal: help quota

Every account gets 2G of disk and 200,000 files (with a little room over both for a while), 1G of RAM, 200 processes and one CPU.

quota -s      disk used and the limit
du -sh ~/*    what's taking the space

When a program runs out of memory it gets killed, and when you hit the process limit new ones won't start. Nothing is wrong with the server when that happens, it's the limit.