Java script error - AJAX

After completing following steps i get javascript error.
Line: 367
Char: 1
Error: 'Ajax' is undefined
URL: http://localhost:8080/display/DIVING/Home

1. Install Confluence 2.0
2. Setup Custom
3. Embeded DATABASE
4. Create Space: KEY: DIVING
5. View DIVING Space. (It displays View Tab)
6. Java script error gets generated.

Also if you go to Edit tab than switching of Rich Text and Wiki Markup tabs doesn't work becouse of similar javascript errors.