Once in a while I have a temporary problem with the hardware of my laptop. It's a Dell Inspiron that was originally loaded with Windows Vista which was never used and then completely replaced with the ArchLinux distro.
However, I had to dig around a bit for drivers for the software. The problem is that they sometimes stop working. This morning my wireless card didn't work until I restarted computer, and last night the display on the laptop went into a test pattern (red/green/blue and black/white flashing) when I launched Xwindows.
I have no way to determine exactly why this happens once in a while. I hate that computers are so complex now that almost anything could be the cause of the problem and it could be a simple random bug.