Want to resolve 80% of the technical problems you will encounter with your Mac? Follow these two relatively simple steps:
1. Reboot your Mac and simultaneous hold down the command-option-p-r keys. If you do this properly your Mac’s screen will flash and it will cycle a reboot. Keep holding down the keys until your Mac chimes twice. What you’re doing is resetting a chunk of memory that stores settings for all kinds of settings (see below for specific details). Clearing up these settings often resolve wacky problems like screen artifacts, sticky keys on your keyboard, and a lot more.
2. Now restart in Single User Mode by holding down the command-s key (thanks Eduardo!) while your Mac is booting. If you’ve done this successfully, a bunch of Unix code will spew across your screen. Don’t worry! You’re just looking at the underbelly of the beautiful Mac OS. Wait until the text stops scrolling by and you will see a flashing cursor at the bottom of your screen. All you need to do is type:
/sbin/fsck -fy
and hit the return key. fsck is pretty much like the Disk Utility app except that it runs outside the operating system. Like Disk Utility, if it encounters any problems with your files, it will automatically repair them.
Tip: if you run fsck and it says everything is OK but it reports the disk was modified, then run fsck again to ensure there are no problems.
If fsck reports that the problems it encountered couldn’t be resolved, I recommend taking your Mac to the Genius Bar or other authorized Apple repair center. If you’re adventurous, then you should consider purchase some industrial-strength disk utilities like TechTool Pro, DiskWarrior, and/or ProSoft Drive Genius. My help desk uses these tools to repair hard drives so that we can recover data. We then “nuke and pave” the drive by formatting it and reinstalling the OS from scratch.
References
Resetting Parameter RAM: http://support.apple.com/kb/ht1379
Single User Mode: http://support.apple.com/kb/ts1417
Resolving startup issues: http://support.apple.com/kb/ts1417
Tech Tool Pro: http://www.micromat.com/
DiskWarrior: http://www.alsoft.com/diskwarrior/
ProSoft Drive Genius: http://www.prosofteng.com/products/drive_genius.php