Dear all, I recently made an observation which some of you on the list may find useful and maybe will save you a bit of money as well. I recently had an HBO 50 bulb which failed after only 69 hours, while usually we run them at least 150 before changing. By failing I mean that it would not start in the morning when the confocal was switched on. I changed the bulb and the next HBO ran without any problems for over 200 hours and was still going strong when I changed it for a new one. This bulb started first time after I had installed it and worked for the rest of the day without any problems. The next day the lamp wouldnt start, even after repeated resetting of the power supply. I couldnt believe that it was caput already and noticing that the room was quite cool due to the airconditioning I tried warming the bulb up with a hair dryer. After about 15 seconds with the hair dryer, I tried again and it started first time without any hesitation.This bulb is still in and going well (touch wood) after over 100 hours. It occasionally will not start first thing in the morning when the room is at its most cool but now we know what to do it is only a minor inconvenience. Once the bulb starts of course the hairdryer isnt needed any more as the bulb generates more than enough heat to keep itself happy. I do not know whether any of these symptoms and circumstances fit with other users (doesnt like to start early in the morning in a cool room) who have had failures but at least with me this problem appears to be due to overcooling rather than the more expected overheating of the bulb! I hope this is some help, Matthew Dr. Matthew Hannah Institute for Neurobiology, Im Neuenheimer feld 364 D-69120 Heidelberg, Germany WWW: http://129.206.50.220/Neurobiology.html Tel: ++49 (6221) 54-8320 or 54-8692 Fax: ++49 (6221) 54-8301