This error may be caused by the name of your file. If you are using certain characters such as #, % or ! in the file name then try to take them out and use only letters and numbers.
Another thing to try would be to turn off the Word AutoRecovery feature by going to File, Options and then the Save tab and unchecking the box that says Save AutoRecover info every:. Then close Word and do a system cleanup using the free CCleaner to remove all your temp files.
Next you can try to delete the Normal.dot file with Word closed. When you open Word again it will create a new Normal.dot file. You can do a search of your hard drive for the file but make sure you have the Show hidden files and folders option checked in your folder options.
If nothing seems to work then you can try a repair installation of Word. Go to Programs and Features and click on Word or Microsoft Office if you use the Office suite and then use the repair option to have Word repair any corrupt files. Or you can uninstall Word and then reinstall. I would suggest running CCleaner after the uninstall before reinstalling.