Has anyone been monkeying around inside the case? It could have all sorts of software issues or one hardware problem that's gotten worse. As this has gone on for a while it's hard to say. It's even harder because we know nothing about your system - make and model, CPU, RAM, operating system, any spyware/adware/virus protection, and specifics about the system.
Give us a few more clues. Does the roommate have any ideas? It may be time to head on down to the local shop, but let's see what you can tell us.