I had previously installed Netscape 6.21 when I installed Mozilla 1.0. Mozilla would not display certain web pages correctly. Some sites like www.ivcusa.com and support.veritas.com would not display at all while others like www.tek-tips.com would not display correctly. Netscape was also affected! It would not render web pages correctly after installing Mozilla. IE 5.5 was not affected. Uninstalling both browsers and installing Netscape 6.23 did NOT correct the problem. FIX: After reinstalling Mozilla (build 2002061707) and moving the cache from the default location to another location corrected both Mozilla and Netscape.
Installing Real Player also caused the same problems in both Mozilla and Netscape. Clearing the cache resolved the problem.
reporter (James) sounds very much like you were using the same profile in netscape and mozilla, which is something that must be avoided... marking this as a dupe of the most recent related bug I found. if you actually did use the profile manager to set up a different profile for mozilla, then please reopen this bug... *** This bug has been marked as a duplicate of 151799 ***