I've been helping the EU Mac users, but since most are playing now, i'll help out here until EST launch happens in enUS.
Here's Blizzard's link to suggested Mac Fixes:http://us.battle.net/support/en/article/diablo-iii-installation-troubleshooting-mac
Note in above, Hard Disks with FileVault and FileVault 2 enabled, cause install problems.
Also note in above URL, if your Macintosh HD or secondary drive or external is formatted to 'Case-Sensitive Filing System', the D3 installer will have a reallllly hard time. It actually will try to install - it won't error out at the start, but somewhere through the % of the initial install.
Using Disk Utility in Utilities, check File Permissions, and also check the drive itself (can't repair unless you boot from Recovery Disk (Lion or CD-ROM if prior).
Other handy things to do:
- Reboot Mac if you haven't in a few weeks or months. I know, I just about never reboot mine.
- Flush the DNS and reboot your cable/DSL/3G/4G modem. To Flush the DNS on Leopard, Snow Leopard, or Lion, launch Terminal from the Utilities folder, the copy&paste or type the following into Terminal:
Hit enter, and then reboot Mac, cold-boot Modem/Router(s), access points, the works.
- Another great tip, reboot your Mac and hold down the left Shift key during the entire boot-up procedure, up to the user password screen, or if you have no log-in, to the desktop. This is essentially 'old school' Safe Mode, or otherwise known as 'Extensions off', not that we use extensions anymore, but I digress and i'm rambling...
- If you believe it may be a Hard Disk issue, as a test, try installing onto a 8GB or larger thumbdrive, or USB Memory Drive or Memory Key. If it installs fine, well, you have your answer. It'll run dog-slow on the drive though. Your next step would be to get an external USB 2.0 or Firewire 400/800 drive, Thunderbolt array, etc.
- If you're running this off BootCamp (for some odd reason!), and you're having install or play issues, you'll want to run Apple Software Update on the windows side of things, grab any and all updates, and also want to make sure you ran the CD you should have burned at the time of BootCamp creation - the BootCamp Drivers etc Disk. That has all the drivers for things like the thin Mac keyboard, Apple mouse, Device Manager bits and pieces etc.
- If you're running Lion 10.7.3, grab 10.7.4. Yes, it's huge, but apparently Apple updated a number of vid card drivers, and they patched up other issues. Hey, it can't hurt! Other than your monthly bandwidth allocation.
- If your game play is fine, you can login, etc, but from time to time, there's choppiness, or sudden performance losses, skipping audio etc - it is likely that some intensive background I/O operation is slowing things down. If enabled, turn-off Time Machine in system preferences. Don't forget to turn it back on when done playing. Also, since you installed 8GB of game files, Spotlight will be quite eager to re-index Macintosh HD (or external HD). You can go to Spotlight in System Preferences, click the Privacy 'tab' or button at top, and add Diablo III to the exclusions list. And who cares if you can't context-search Diablo III !