Are you worried after seeing blue screen on Mac at startup? This type of incidents might occur during Mac startup which means everything is not fine in the system. Occasionally after opening the system user experience blank screen that turns into blue. At this moment system finds the address of OS X but due to certain issue in registry Mac failed to boot. In order to resolve blue screen on Mac at startup there is need to use disk utility for repairing permissions. Alternatively running fsck in command line is another option. Ultimately if the problem still pertain, format the hard disk and reinstall OS from original disk.
Though this way it is possible to fix blue screen on Mac at startup but you need to understand that after doing this there is deletion of data takes place. In Mac user would capable of getting lost file back through updated backup which is provided by Mac built in utility as Time Machine. If somehow this utility does not ensure restoring of missing data then look for third party program. Mac Data Recovery Software is eminent and excellent tool for retrieving each type of damaged or lost file without much hassle. Fix blue screen on Mac at startup now.