You are not the only one who gets this error. The generic "Microsoft Word has Stopped Working error" occurs often. Firstly make sure that you have a genuine copy of Microsoft word. There are a lot of pirated copies floating around, but since these are 'cracked', stability is not guaranteed. If your copy is genuine and you are getting this error, read on.

The Cause of Microsoft Word Has Stopped Working
A common problem is that this errors only occurs with loading some documents that are corrupt. If that's the case, there is not much you can do besides from starting over from scratch on that document. However, a more common cause is the shared dependency problem.
Windows 7 or Windows Vista programs share a lot of components. It doesn't make sense to write the same code twice if they can reuse it right? This is true, but shared components and dependencies have downsides too. The problem is that when those shared components become corrupted programs which use these components might crash unexplainable. The "Microsoft Has Stopped Working Error" is one of these generic errors.

The Fix: A Full and Complete Reinstall
A normal reinstall won't fix the problem. Uninstallers tend to leave a lot of junk data at the system. This includes user profiles, registry keys and temporary data. When you reinstall, the corrupted dependencies won't be installed as they are already present on the system. The proper way to do it is to uninstall word. After that, remove all temporary files, associated registry keys and shared dependencies.

Reboot windows and reinstall word. Hopefully this will fix "Microsoft word has stopped working". However, you should remember that keeping your system health good with a registry toolkit is far better than fixing it manually afterwards.