Mozilla and Netscape X do share the same configuration files, and they DO NOT play well together sharing the same files. The easiest thing to do is stay with one or the other. Since they are basically the same, with Mozilla being the one on steroids, I would recommend Mozilla as the web browser of choice. I had a similar problem with Mozilla and Netscape locking up at startup. The culprit is the prefs.js file getting corrupted by Netscape. This is the one file you NEVER WANT TO corrupt. prefs.js contains all the information regarding your security info, mail settings, mailboxes, etc... Believe me, once you get this problem straightened out, backup that file in case it gets botched in the future. To fix this, archive EVERYTHING in the /User/Library/Mozilla into a stuffIt file (use DropStuff on your computer). Then run Mozilla OR Netscape, and stay with the one your will ALWAYS use. You can unstuff your Mozilla folder archive to the desktop and look inside the files individually using your favorite text editor (ALL of Netscape's and Mozilla's files, for the most part, are text files despite what the "dot-two or three letter" extension says). I bring you this kindly information from my personal experience of resurecting Mozilla from the dead.