With 6u10(old PLug-in) Mimetype "application/x-java-applet" inside the embed tag is not working without "version" information. With new Plug-in it's working fine inside FF3 and with old Plug-in it's working till 6u5 but not with 6u10.
Try following applet
http://sqeweb/deployment2/jitu/deployment_mustang_exec_ws/deployment/src/plugin/runtimeArgs/runtimeArgs/html/secure/TestUntrustedSecureOENoVersion.html
- With FF2 or older verions of FF,which always uses old PLug-in, applet will fail to load and complain about missing Plug-in
- With FF3 : It will work with new PLug-in but not with old PLug-in.