Silverlight not working in Firefox 3.6.12

Question

We are having some wierd behavior in firefox with silverlight. We have tried everything and I am hoping for some more ideas. Below is the behavior

1. Install firefox (3.6.12) and silverlight (4.0.50917.0). The versions there are locked and not controlled by us and on all our users machines.

2. Visit our silverlight application (also tried simple application with just a background)

3. Instead of seeing our application, you see "Get Microsoft Silverlight" -- (about:plugins reports silverlight 4.0.50917.0 installed and enabled)

4. Visit site in IE, app works

5. Install or uninstall any plug-in (tried Firebug and IETab2)
6. After install, click "Restart" when prompted
7. After FF restarts, silverlight works as expected
8. Close firefox and reopen.
9. Once again, silverlight is broken

Any ideas? We tried the CWDIllegalInDllSearch entry in the registry to no avail. Please help!

Answer 1

I think it is a problem with Firefox that has been fixed with Version 3.6.14. See this BugReport on Bugzilla. A memory leak in prior versions, cause some problems in the Silverlight detection script of Firefox.

I can only suggest to update Firefox to version 3.6.14. But before i would try it in a local test environment to check if its really a bug in Firefox.

Update: It seems to be a general problem with Firefox 3.6.x, cause some users report the same error as your with higher versions than 3.6.14. See here and here.

Answer 2

The only thing that springs to mind is disabling the plugin-container

• In Firefox address bar type about:config
• Read the warning, choose your preference to always remind you or not and accept
• In the search bar of the config options now type: npctrl
• You should then see the entry: dom.ipc.plugins.enabled.npctrl.dll
• Change the value from true to false (simply double-clicking will change this for you)
• Restart Firefox

EDIT

There is another workaround which is to disable then re-enable silverlight plugin. Rather than re-isntalling.