Dirty memori(es)
Here's one from the archives! We had a laptop brought to us a while back that wouldn't boot up. We ran through the normal diagnostic routines on it, checking the basic hardware and peripherals, but nothing seemed out of order.
As a long shot, we decided to remove the memory from the computer, clean it with circuit cleaner and reseat it. And lo and behold, it booted up fine and continued to run properly ever since then.
So if your computer suddenly stops running normally or won't boot up then it doesn't necessarily mean there is a serious problem or requires a major repair. Not that it will always work to do the step above, but there are a myriad of things that can go wrong with your computer, so don't panic, if something goes wrong just get in touch with ExpatTech!