/sitefinity not loading

Hello,

 This morning I added a 'Recent news' widget to our dashboard and ever since the /sitefinity admin area won't load.

 When I delete my cookies, I get the option to login again. It says that my username is already logged in. But after I login the loading gets in some sort of infinite loop.

I don't get any errors, the EventViewer doesn't show anything.

I tried to delete the widget I added in the database, but I have no idea where to look.

 Can anyone help me?

 Gr. Chris