I've got this error as well.  But it only started happening when I converted my project from Visual Studio 2005 to Visual Studio 2008?   Anyway I have uploaded a new Visual Studio 2008 project I created that reproduces the problem.  Note the problem only happens in IE7 with Tools | OPtions | Advanced | Browsing | Disable Script Debugging (IE) is UNTICKED (that is it enables script debugging)... so normally you wouldn't see it.  

 

Could you please have a look at this ASAP.  Thanks.