When I connect any Android Smartphone which I previously used to debug to my pc, normally it automatically sets the debug mode enabled. Somehow since a few weeks my HTC one X stopped doing this. Everytime I connect my smartphone I have to manually select the USB Debug mode to be on.
UPDATE
It looks like the bug could be even worse. If I switch my top right button to on, but leave the bottom "debug mode" off, my phone still starts debug mode. After a while it somehow detected that it wasn't in debug mode and jumped back out.
The solution was simple, simply disable and enable the Debug options (top right button "ON")
UPDATE Though it worked for a day or so, the trick didn't last long
UPDATE Software update did the trick. Apparently this bug was only present in 4.2.2 (at least in combination with HTC sense)