This is a strange problem.Although, i could not come to the bottom of it. This is how i got rid off it. 

1. Even though, you are getting this exception and loads of them, be patient, the page will load eventually.

2. Go to administration (top right corner).

3. Upload the xwiki-enterprise...xar file (please note the extension xar). When you import the file and load all the templates, it seems all the wiki preferences get set.

4. While loading this xar file and its contents, I got an error message on the screen.

5. I ignored it, went back back back and then registered myself as a normal user and then everything was fine. The Exceptions are gone !!

Samudra