Error on opening the site

Hi,

I don't know what happened, but sins today i get this error when opening my site http://www.yinimportexport.nl:

We're sorry, an internal error occurred.

Our supporting staff has been notified of this error and will address the issue shortly.

We apologize for the inconvenience.

Please try clicking your browsers 'back' button or try reloading the home page.

If you continue to receive this message, please try again in a little while.

Thank you for your patience.

also the admin page doesn't open.

Some help will be great !

Turn off the custom errors mode to see detailed errors
http://docs.nopcommerce.com/display/en/FAQ

(Or, if you can query the DB directly, query the Log table)

If you can't get into the admin side, then it's usually a server-related error.

Try recycling your application pool in IIS and that may fix the issue. It happens to me frequently since I upgraded to Nop 4.0 and try to restart the site through the admin interface.