Server Error in '/' Application.
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Runtime Error
Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.

Details: To enable the details of this specific error message to be viewable on remote machines, please create a tag within a "web.config" configuration file located in the root directory of the current web application. This tag should then have its "mode" attribute set to "Off".











Notes: The current error page you are seeing can be replaced by a custom error page by modifying the "defaultRedirect" attribute of the application's configuration tag to point to a custom error page URL.

I have it installed on Vista. Vista is just a fail of an OS and doesn't like anything that isn't Microsoft...

Edited**

Make sure you have full rights on your computer before you continue. It can be that you don't have admin rights.
As the error says you have another application/setup running. Did you just install/delete other programs that required a reboot that you ignored or didn't finish as it should?