Hello everyone, long time lurker, first time poster here! I've been experiencing some very strange things so I figured I'd share it with you. This might become almost like a infamous "wall of text" but.. bear with me. A year ago my iMac (the one in my signature) said goodbye and gave me nothing but a questionmark-folder at startup. I learnt that it meant my poor little friend couldn't find the startup disk. I went ahead and put in my OS installation disc and checked the volume with Disk Utility. Sure enough the errors were more than plenty. After thousands upon thousands of "b-tree error" and "keys out of order" it finally reached a conclusion; the volume needed repair beyond what the Disk Utility was prepared to offer. I wanted to let DiskWarrior take a look but I never got a hold of a working disc of that application. Slowly my hope of regaining access to my personal files was shrinking into a sad little raisin and after a few days I decided to go for a fresh start. A few tweaks, apps and other stuff could be sacrificed. I erased the harddrive completely (I also tried the "write to zeroes"-option) and installed the OS again. Ladies and gentlemen we had LIFE! It was amazing to once again see the desktop I once learned to love. But I soon realized that everything wasn't what it should. Some of the ducklings were not in line so to speak. During one of the updates (as the system was set back a year or two due to the old OS-cd) the computer froze and then there was... darkness. I tried to boot it up again but the questionmark-folder was back. Disk Utility said the same thing again. I raised my arms towards heaven, fell on my knees and gave up. One year later, namely last week, it occured to me that I wasn't completely happy with my Windows-laptop that I used as a substitute. I missed my iMac and decided to go for another shot. I purchased a brand new harddrive, this time 500GB, made sure it was compatible, downloaded a PDF with instructions and went to business. A minute or two later my iMac was ready for a new OS-installation. Everything went smooth and no errors were to be found. And here's were the worrying things yet again starts to happen. Everytime I choose to reboot the computer, the questionmark-folder appears. It can not find the startup disk at all, and the Disk Utility says the volume (neatly named Coraline after the amazing book/film) needs repair beyond what it can repair. But - and be warned, now it's getting really strange - if I always choose to completely shut down everytime it needs to reboot, it works fine. It starts in a few seconds and shows no signs of trouble what so ever. My questions are as follows: Is there any known causes of this behaviour? Could the whole system crash at any time due to the mysterious errors that I'm currently successfully ignoring through avoiding the reboot-option? If yes on the previous question: How could I ever gain confidence enough to start poking around in my already fragile system? Finally I would like to say thank you for reading all the way through (if you just skipped here directly from the top I would just like to say: Hi! I'm Starfighter! 'zup?) and thank you all for so many hours of interesting reading and for all the countless good advices I've assimilated browsing the threads and... Yeah. I'll leave it at that.