The address book is normally located in C:\Program Files\Outlook Express, and is *.WAB. The file can be copied with Explorer and saved to a diskette. If you have more than one computer and want to "sync" your address book, that is an easy way to do it. Just make sure the same one is in all systems.
To test the condition of the file, open Outlook Express, then from the menu go FILE, EXPORT, and select Address Book. That gives you a couple of choices . . . take the Microsoft one and see if it will create the export file. If it can't read the source, it will not be able to do it.
To destroy the address back and create a new one, just delete that .WAB file (after you have copied it) and then let OE start over. If that still crashes or locks up the system, then the problem is in Outlook Express and you may need to reinstall it (goes with IE.)
Assume you are running XP? If so there are some more options depending on what you find out about the .WAB file. (System Restore to an earlier date when it was all working OK.)