Try starting your computer in Safe mode and then starting Word. Same problem?

If so, take a look at the AutoCorrect backup utility on the MVP website.
http://www.word.mvps.org/FAQs/Custom...utocorrect.htm

If it isn't a problem when your computer is in Safe mode, then the problem is some third-party program on your computer. Perhaps you loaded one to add AutoCorrect to your browser and other programs.