I have now read some more info about the subject and concluded that threre is some kind of incompatibility between daemontools 4 and nvidia raid drivers.

I just tried to mount the image from my USB 2.0 externa drive and it worked perfectly when the IDE-controller was disabled. So obviously Starforce does something through daemontools which results in instant reboot if the image resides on an nvidia raid partition. However if you mount the same image on an USB drive (or maybe an IDE based drive) it works perfectly...