If I try to login on a Debian with XFCE it gets a blackscreen for a few seconds, then it flashes really short and puts me back at the login screen. 

The strange thing is, if I go into a terminal using Ctrl + Alt + F1 (Or any other F key) I can login, and get into the GUI using startx. 
Everything works like usual. 

I installed Debian the same way on 4 different machines but none of them had this error.

I used debian-8.2.0-i386-xfce.iso for installation with a USB stick.

Somebody has a idea what could cause this behavior?