Upgrade to FireFox 3.6 might be a pain under MacOSX. Under our MacOSX 10.6.2, all Java applets were broken after FireFox 3.6 upgrade. The solution to fix the problem is to follow:
https://support.mozilla.com/en-US/kb/Tr ... ng+plugins
In short:
1 - Find pluginreg.dat
2 - Close FireFox 3.6
3 - Delete pluginreg.dat
4 - Restart FireFox 3.6
Then Java support under FireFox is back (and JFileUpload works again)