Sounds like possibly your cpu is overheating and shutting down your system, make sure all your fans are working properly. If cat hair is problem go by a can of compressed air and blow out the inside of the computer and be sure not to turn the can upside down when your spraying or else it will drip out and possible damage your system board. Also in your bios setup it will tell you what your cpu temp is, cant recall off top my head of what title its under.