While a computer may seem arbitrary, it is too stupid to be so. Arbitrariness takes free will and a computer doesn't have it, evidence to the contrary aside. Learn to observe your actions immediately prior to a freeze up or other mysterious action. They may give a helper an important clue. This doesn't mean you are at fault.
Computers are a moderately complex device, contrary to advertisements.
It does take some effort to achieve proficiency. Computers can't handle as many simultaneous actions as you can. They just shut down sometimes. Just close it down and start over. And remember to save your work frequently.