As you know, I’m a web developer. Most users uses Micro$oft Internet Explorer as main browser. Developing web applications for this browser is a real nightmare. You must lead and deal with strange and non descriptive error messages. This causes a lot of lags in software development, you must be a kind of illuminated developer to guess which is the real error. While you get the things working on Firefox, Opera, Konqueror and Safari, on IE Internet Explorer you get things like the next screenshot.
Again, I ask for some business facts: where is the most productive platform that Micro$oft proclaims?. Really I don’t know where is productivity while must deal with these kind of errors, with this kind of messages you never will know how, where and what is happening with the software that you are developing.
Yeah!, there are some debugging tools, such as Visual Studio 2003, Visual Studio 2005 and Visual Studio 2008, but adding the cost of these bloat environments to debug JavaScript has no sense. Main, because all the other browsers offers real options to work with AJAX and similiar technologies.
You will say: but you can get Micro$oft Script Debugger. Really this tool is completly broken from Winblows XP to Winblows Vista, while XP is most used Toy Operating System on the Internet.
Dammit!, why most users can lead with this kind of browsers. You can visit arround 50 pages and you will get contaminated with malware of any kind… I really don’t understand…
Remember to call m-x doctor in emacs if you have developed software for Internet Explorer ;)

Have you tried DebugBar?
http://www.debugbar.com/