The resource cannot be found

I installed Sitefinity Beta 2 and upgraded my project. When i open the admin "Profile" i get this error:

The resource cannot be found.

Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable.  Please review the following URL and make sure that it is spelled correctly.

Requested URL: /Sitefinity/Profile

This problem does not occur with newly created projects. I have also had this problem earlier with Beta 1 when editing users or changing permissions. Strangely this was solved after editing and saving my homepage (?).

Hi  Coppen,

Could you check the fire bug console and what is returned by /Sitefinity/Services/Security/Users.svc. It is possible that the ID of the user is somehow not correct and the web service fails to retrieve your data. Before we call the web service there is a GET request to "profile" page. If you reset the database does the issue still occurs?

Kind regards,
Ivan Dimitrov
the Telerik team

I don't know where to look in the Firebug console. The page source returns "File not found exception", but what do you mean exactly?
When I browse to /Sitefinity/Services/Security/Users.svc, a JSON file is downloaded containing correct users information.
And how can I reset my database? As I have mentioned before, newly created projects don't have this problem.

Hello Hugo,

We cannot reproduce this issue locally when you upgrade from BETA1 to BETA2 and it looks like that you have made some changes before you get this error. You can use the newly created projects where the issue does not persist and send us the problematic project and its database.

Best wishes,
Ivan Dimitrov
the Telerik team