SharePoint writes 'Unknown Error'

The following post was very helpful:
http://koenvosters.wordpress.com/2009/08/06/showing-the-real-error-message-in-sharepoint/ - It Shows how to set the IIS to display the full stack trace.

ASP.NET Error: The resource cannot be found

Check the following:

1. Check that the target resource exists.

2. Check that ASP.NET is enabled on the IIS:
A. Open: Administrative Tools => Internet Information Service (IIS) Manager
B. Expand the server, click on 'Web Service Extension'
C. Verify that ASP.NET is set as 'Allowed'. If not, change it.

Using multiple JavaScript libraries (Prototype, MooTools, jQuery)

I'm a fan of MooTools (a JavaScript library), and most of the tools I use are based on this library. That said, one of the best JS around is LightBox, which is based on Prototype. However, when I tried using both MooTools & Prototype libraries in the same webpage it failed. I was sure there's a solution so I kept digging in, but I couldn't find any.

Another JS library - jQuery has a special computability function called noConflict which solves those problems, but both MooTools & Prototype lack that functionality.

The only solution I could find: Choose one library - MooTools or Prototype, and use only that library. There are similar implementation of most tools in both libraries.