That sounds like you have a virus in your computer that is attacking Microsoft Word. I suggest virus protection software or spy ware protection software to fix the problem.
Do you have more than one application open? Sometimes if you have numerous software applications open and an older model computer, that can cause major lock ups on what you are trying to do. I suggest closing all other softwares except MSWord and go from there.
Check your harddisk for bad sectors. Word does temporary backups of what you're writing... probably one of the backup hit a bad sector and locked you up. Scandisk c: to fix
