i bought a used HC 4900 this week. The picture looks great and everything works fine. Unfortunately, after around ten minutes, the HC 4900 shuts down. The fans are still moving for a while, but the lamp is off. While this, the STATUS-LED is blinking green. The manual, as far as i can see, has not hints on this issue. This is why i am asking here. The bulp is new. The previous owner told me that he did not have this problem with the old bulp, which I unfortunately do not own. Any ideas? Is the bulp, even if working for 10 minutes, the problem? Thanks for your help!