The program has nothing to do with profile, where bookmarks, mail and address book reside. Too bad I did not notice your post, but, i don't expect that replacing the program will accomplish anything. The problem is most certainly in the User profile. One finds the program or Communicator in the same directory as the User profile. Both are in separate folders. The normal path is:C:\Program Filres\Netscape\Communicator and Users. My recommendation is to close Netscape, access Windows Explorer as outlined above, and open the Users folder|profilename|Mail, most likely default.
Local the Inbox.snm file, known also as header file, and delete it. Close Windows Explorer, and open Netscape again. If it is what I think the faulty header files should be rebuilt correctly.
As for the installation, assuming that there is something at fault with the program, it is best to uninstall with the Add/Remove of the Control Panel. The Users folder is not affected by the process. Then one can install the newer version (4.8 is the latest).
Installing on top without information about the version (you just said 4.x) is a bad idea. The idea that all ills will be cured by reinstalling the program is still around with v.7.x, and is causing havoc, but you, probably, can get away with it using any 4.7x version. I would uninstall any earlier version.
An you can do a backup anywhere on the hard drive, if there is no CD-ROM. A floppy may work, in a pinch
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041108 Firefox/1.0
