Here's what I found:
http://discussions.info.apple.com/thread...ID=2630327&start=30&tstart=0
Short answer:
sudo pmset -b hibernatemode 25
Long answer:
(I do apologize for the formatting of this, but it appears that the forum-interface won't let me organize it as cleanly as I'd like.)
Hey folks, recently got the 13" Air and discovered this quaint little error for myself, to my horror, as it's the purpose of an ultraportable-computer is somewhat hampered if it can't fulfill its function as portable.
So, before I entered into a full-on panic, I resolved to troubleshoot the issue, beginning with PMSET...
... and it seems I was successful.
I've seen that other people here have also resolved the problem (to varying degrees) with PMSET, but as yes a walkthrough as yet to be posted.
I think I'll help with that:
1) Type 'terminal' into spotlight; (this will bring up the command-line interface to OSX, which we'll need to use to address the issue)
2) Press Command+T to open a new tab;
3) Type 'man pmset'; (this is the manual to pmset, use spacebar to advance a page or the up and down arrows to scroll-by-line, Q to quit.)
4) With your new tab open as a reference, go back to your first tab and type 'pmset -g cap'; (this tells you what your system can do, and you want to make sure deepsleep is there,
elsewise your problem is beyond the scope of my tutorial.)
NOTE: Steps 5 through 7 address troubleshooting, you may wish to skip ahead to Step 8.
5) Now that you know your system can hibernate, you may want to troubleshoot what causes the problem, to achieve this you can reduce the time it takes for your machine to enter deepsleep/hibernation thusly:
sudo pmset -b deepsleepdelay 10
(NOTE: It appears that deepsleep WILL NOT activate when the computer is plugged-in. Additionally, the number provided is in seconds, so here I've changed the delay to 10 seconds; the default is 4200.)
(NOTE: About sudo: You will be asked to provide the admin's password, and as there is no backspace you must enter the password precisely. Additionally, you may not be able to invoke sudo even with the password unless your account has admin status.)
6) You may now, if you wish, unplug your computer and place it in sleep, listening very closely for its fans, as they will turn off when the computer enters regular sleep; furthermore you may hear the system temporarily reactivate while preparing for deepsleep, and this at least tells you the process is moving on along.
7) Assuming you've entered deepsleep you may now attempt to reactivate your machine, though doubtless this is the point where your system has, unbeknownst to you, elected to reboot instead. Bear in mind, though, that even with a properly functioning deepsleep, the computer takes a few seconds to read the data from the completely silent Solid State Drive; again, listen for the near-silent fans to clue you in to the processes of your computer.
8) To change the way your system enters deepsleep, use the following command:
sudo pmset -b hibernationmode 25
(Now then, I'm sure you're asking: Why 25? In short, because it's one of the few numbers pmset itself recommends, and furthermore, the description of Mode 25 more closely aligns with the advertised behavior of the MacBook Air than did my default of Mode 3. Indeed, I believe this one setting is the cause of the problem people have been experiencing. In the event that even Mode 25 fails, you may take some solace in the ability to disable deepsleep by using Mode 0, though at this point I'd recommend talking to Apple Hardware Support.)
The error was resolved for me at this point, but I must again emphasize that, even when properly functioning, wake from deepsleep takes a little longer than you might like, and is exacerbated by the complete absence of visual feedback.
MacBook Air 13" Mac OS X (10.6.5) PowerBookG4AL 12"; Discrete MacBook Pro 15"