When I change the product image I´ll get logged out. Why?

As the title says, When I want to change the product image I´ll remove the old and choose the image I want to use and click on it. Nothing happends for 2 sec and the I´ll get logged out. Instead of the image I´ll get the loginpage where the image should be and under that it says Se the attached image!

I use 1.5.1.3. It has worked before.

Grateful for answer! I am i a hurry..

Regards
Jaeger

Something has obviously changed or been changed in the admin files.

If you know what has been recently changed, change it back until you figure out why it is breaking your admin.

Last resort is t ore-upload the default OpenCart admin files.