If you upgrade to 10.3 from an earlier version of OS X instead of doing a full install, chances are that Java is broken. To see if you are affected type java -version in the Terminal. If you see the following line, you are affected:
HotSpot not at correct virtual address. Sharing disabled.
Apple has a Knowledge Base article (#120242) about this. You can also find some workarounds at this Readerware page. The second suggested workaround looks the most promising:
After installing my copy of Panther, I encountered the very same error as you. However, I was not about to perform an "archive and install." Instead, I renamed:[robg adds: I reformatted the quote a bit, but changed none of the content.]/System/Library/Frameworks/JavaVM.frameworkto/System/Library/Frameworks/JavaVM.framework.offeffectively removing it from the installer's path. Next, I loaded the Panther installer, and I performed a "Custom" install of ONLY the "Essential System Software" (which includes Java).Long story short: this works. Panther does not find an existing JavaVM.framework, and thus it does not get confused. When it finishes, you will find a brand new JavaVM.framework directory, and "java -version" reports "builder 1.4.1_01-99", as it should. Once I was certain everything worked, I then deleted the JavaVM.framework.off directory that I had moved aside.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031028151229265