Mac OS X 10.5 blue screen at startup is big problem that can make all you stored data in the Mac hard drive inaccessible. The System will not boot and will stuck on the blue screen. This problem occurs when there is any corruption issue with the start up disk or the operating system files are misplaced or damaged. It can be due to accidental shut down, file system corruption, error while updating the Mac OS X. So to fix the Mac OS X 10.5 blue screen at startup problem you will have to fist use the disk utility to repair it and format if needed then you will have to reinstall the operating system in the Mac. When you do that the files on the Mac hard drive will be deleted but they can be restored by using the time machine backup. If the time machine or any other backup source is not working then you can use the Mac data recovery software to get back all the files. The recovery process is simple, easy yet effective, so you should download the software and use it when you fix Mac OS X 10.5 blue screen at startup.