Problem with browser communication in IE

I'm working on a small game where the game is initialized using browser java-script.

Basically the workflow is like this:

 step 1 (Unity):
 function Update()
     wait 10 frames
     if Unity has not recieved any call from Browser
        Application.ExternalCall("UnityInit",0); // let browser know Unity is started
 
 step 2 (Browser):
 function UnityInit()
     Wait 10 ms
     Call the method WebsiteRecievedJS on object Init (Unity)
 
 step 3(Unity)
 function WebsiteRecievedJS()
     // now Unity knows that Browser communication is ok
     Application.ExternalCall("UnityReady",0);

 Step 4: (Browser)
 function UnityReady()
     // setup Unity
     // Call InitDone

 Step 5: (Unity)
 function InitDone()
     // Load main menu

Step 2 and 3 is actually not really needed. Their purpose is to reach a state where both Unity and Browser knows for sure that the browser-communication is established.

This works fine in Firefox and Chrome, but on some Internet Explorer installations, the browser never receive the UnityInit(). If the IE runs with the Javascript debugging on, everything works.

Has anyone experienced problems like this. And is there any workaround for the problem?

Also I'm interested in knowing how many people have the problem. So if you see the bug, then report back in a comment to this post.

The full source code can be found here: http://dl.dropbox.com/u/6024335/BrowserCommunicationTest.zip

And the problem can be seen here: http://www.kickstartgames.com/browsertest/index.html