Computer freezes used to be common for systems running anything from DOS 4.0 through Windows 98ME. Microsoft was once notorious for making operating systems that simply froze without warning.
I well remember the first time a computer froze. I had been running DOS since version 1.1 came out and was running a game under DOS 4.0. Everything locked up and I honestly thought I had broken my computer -- I'd never seen one just hang up like that before. Sadly, system freezes and crashes become common..
That all changed with Windows XP because Microsoft seemed to have put in considerable (and commendable) effort in releasing an operating system that actually worked well. Windows XP improved even more with the release of Service Pack 3 and Windows has been very reliable since then. I'll put it this way -- I'm back to the point where I'd assume something had gone terribly wrong if my Windows 8 machine froze.