Java Applet not loading

I am running an FTP server "Rumpus" and generally it works very well.
It does FTP and FTP via HTTP. We use it as an internal FTP server within our company.
However, there is a drag and drop feature that has stopped working on most clients that are connecting using Firefox and Safari.
The problem seems to be that the drag and drop function is a Java applet that requires the client to accept a digital signature, and on almost all machines the window prompting users to accept the certificate/signature never pops up.
The drag and drop feature works on a Windows 2003 server box, and one Mac. The other 35 macs we run all fail to load the applet. The clients connecting are a mix of 10.5.8 and 10.6.3 machines. There is no proxy server, all system updates have been done. Occasionally if I run "cocktail" and clean caches it might work once before crashing Safari or Firefox. I tried Firebug in Firefox but it does not catch anything, no messages in Console either. Under the Java preferences pane, what versions of Java need to be turned on? Any history of other things that might conflict with Java? Any suggestions...


Make sure the Java version selected is current:
Mac OS X has its own built-in FTP server, which is documented here: .html?sort=POPULAR&page=3
And Leopard has one as well:
Finally, if your problem is connecting to another FTP server, SFTP is well done by Fugu for the Mac:
And regular passive ftp is easy with the light mode of 's RBrowser.
Both work well with Leopard & Snow Leopard.
Java is great when it works, but it can get really bogged down if it is a Java client on a PC that requires ActiveX PC plugins. While any Intel Mac can run Windows to act on ActiveX, and possibly WINE, ActiveX based Java is very insecure. I recommend steering away from non-Mac based Java apps wherever possible.