IE8 javascript debugger is now broken

I am on Windows 7, using IE8 and Visual Studio 2005. I have been enjoying the built in javascript debugger in IE8 for several months. About 2 weeks ago, I installed some security update for IE 8 (possibly KB978207) and all of a sudden the javascript debugger is now broken.

If I get a warning from IE 8 that an error occurred and asking if I want to debug using the built in debugger, if I hit yes, I get a grey popup in the top left corner (which I've never seen before) saying "JScript Debugger. Breaking on JScript runtime error - Object doesn't suppo开发者_运维百科rt this property or method". Then nothing happens. IE freezes up and then I get a Windows popup saying that IE 8 is no longer responding and asking if I want to end this process. If I try to end the process, nothing happens and I continue to get the grey popup. I usually have to kill debugging process from VS 2005, but the frozen IE8 still is present. It's not until later when the OS, finally cleans up the process that it will go away...

Edit (new info):

I tried removing the lastest security update and a silverlight update that came around the same time, but Windows automatically reinstalled them....

I then tried removing IE 8, and then adding it back to my system to reset anything related to IE8. This did not have any effect.

After reinstalling IE8, I did notice that, when I first tried to open the developer tools window by hitting F12 from a regular IE 8 window, I never saw anything, but I could see the developer tools title in the task manager list. I had to right click on the task and maximize the window, so I could actually see the developer tools window. Apparently this is a bug mentioned here: http://social.msdn.microsoft.com/Forums/en-US/iewebdevelopment/thread/79b8ee54-c5f6-4467-ba6d-27491c95cd13

I've realized that the window will maximize if the iexplorer.exe process is not the debugged process launched from VS2005.

The grey popup I mentioned in my original post is from the developer tools window iexplorer.exe process.

If I launch my app from VS2005 and then hit F12, I see that the developer tools window is opened (I can see that window is opened under the IE icon in my taskbar), but it is not shown. If I try to maximize it from the task manager, this has no effect.

So basically, the developer tools window is freezing up when it tries to open under my debugged iexplorer.exe process launched from VS2005. The OS then asks if I want to kill the process since it's not responding, but it is unable to kill it. At some later point, the zombie iexplorer.exe process is killed succesfully (by the OS I presume).

Had the same thing happening. You clued me in on the solution by pointing out F12 starts Developer Tools in the taskbar but doesn't show up on the screen. Apparently the window is off screen in nowhere land and causes major screwups if you attempt to debug in this state. So my solution was to:

1. Close all IE instances
2. Start up IE
3. Start up Developer Tools (F12)
4. Hover cursor over the the IE button on the taskbar until context menu shows
5. Right-click the Developer Tools item in the context menu (not the taskbar button)
6. Click "Move"
7. Start tapping arrows until you see the window come back in view. Mine was off stage left so I had to hold down the right arrow.
8. The window will have been sized down to just a window title bar, so resize by dragging the right corner down and out.
9. Once the window is moved back and resized, close it to "set" the position. You should be good to go now.

May be the security patch has disabled script debugging in IE. It was a common problem when using the debugger of VS 200X

Now on try to enjoy FireFox with the FireBug Addon. It's really great to debug Javascript. :)