What happened to IE?
Chances are, what ever caused your problem with IE may be causing the problem with Mozilla. I'm sorry, but I'm not very familliar with Mozilla. (Firefox yes, but not mozilla).
Have you checked/cleaned your system of spyware and viri?
What version of Java are you using on your Win98 system? To find out, go to Start -> Run. Type 'command' (w/o the '). This will bring up a dos window. Next, type 'java -version' and you will be presented with the version of Java that you are using.
Let us know.