How can IE lose ability to execute Java applets?

Question

I have an applet which is used on our company intranet. From time to time there are users who are suddenly no longer able to use the applet and they get an error message.

I notice that the browser (IE6) no longer displays the Tools->Open Java Console menu. Java 1.5 is still installed and I can open the Java settings dialog from the Control Panel. It just looks like the browser has lost the connection to Java. Reinstalling Java fixes the problem.

Most, if not all users, who have had this problem also use IBMs Host On Demand applet which (apparently) has to use Java 1.3. I suspect that the problem originates here but cannot explain it.

Has anyone else experienced something similar? Ideas?

Thanks!

Answer 1

Did you check the settings? You can turn Java off in there.

Answer 2

What about getting rid of IE6 and upgrading to IE7/8 or another browser? Or maybe your antivirus (caused by updates/...) disables the java-applets?

Answer 3

Many browsers can only load only one JRE, and the first one loaded wins.

If a user tries to run an applet that needs JRE 1.3 and then a second applet that needs JRE 1.5, the second applet will only have a JRE 1.3 to run on. At this point the 1.5 applet will fail to load because JRE 1.3 can't run 1.5 byte code.

If your users that don't use the IBM applet can still use the 1.5 applet at the same time as some of the IBM users are struggling, then this might be your problem.

One way to solve this problem would be to use the different applets in different browsers (IBM applet in IE6, 1.5 applet in Firefox, and only have the relevant JRE plug-in installed in each browser.)