A macro virus may use Word’s macro programming language (VBA) to spread itself through your computer, infecting all your Word files. Macro viruses infect Word documents, templates, and other programs that uses a programming language. Here’s how you can reduce the likelihood of getting a macro virus.
Macro viruses do not infect programs; they infect documents and templates. The virus will spread to other documents and templates you may have on your system.

1. Install Microsoft Word anti-virus software: http://support.microsoft.com/support/kb/articles/Q49/5/00.ASP.

2. Set a security level in Microsoft Word – Word 2000 Only.

From the Tools menu, choose Macro and then Security. On the Security Level tab, select the security level you want and then click OK.

3. Protect the global template (Normal.dot).

To prevent some macro viruses, you can apply password protection to the Normal.dot.

To do this:

1 Click on the Normal.dot file and
2 Choose Properties and select the Protection tab.

3 Apply a password, confirm the password and click the OK button.

Or you can set password protection by:

1 In Word, choose Tools, Macro, Visual Basic Editor.
2 In the Editor, click on the Normal project and select Normal Properties.
3 Apply password protection and click OK.

UPDATE: I have had some success in getting Word docs back to normal by saving them to HTML and then re-opening them in Word. Then re-save them to .doc. This seems to remove corruptions due to problems with tables, usually caused by too many table styles causing the Normal.dot to crash.

Please let me know if you know any tricks to recover damaged Word documents.

Related posts:

1. 3 Reasons Why Microsoft Word Documents Become Corrupt
2. How to Stop Word from Opening Every Document Separately?
3. How to Fix MS Word After It Crashes – Fix the Normal.dot file