[Wednesday, February 20th]
UPDATE: The fixes listed below can also help resolve an issue in which external displays do not come on at all while the notebook's lid is closed and will not wake up when keys on an external keyboard or buttons on an external mouse are pressed.
One MacFixIt reader describes this issue:
"When I wake my MacBook Pro in closed-lid mode it shows the desktop picture on the external screen and then goes right back to sleep. If I then wake it again, the same thing will happen all over again. AC power is connected and the mouse/KB are working too so that's not the cause of the problems. Somehow the MBP seems to constantly want to go back to sleep right after it wakes up."
We previously reported on disappearance of previously available screen resolutions under Mac OS X 10.5.2. It is difficult to determine whether this issue is caused by Mac OS X 10.5.2 or the Leopard Graphics Update that accompanied it. A thread on the MacFixIt forums is now tracking the problem, with reader Philip Chadwick writing:
"Using an external via DVI that supports 1680 x 1050?it actually worked fine after the 10.5.2/video updates, but today, after a hard crash/reboot the resolutions above 1400 x 900 were missing. Re- detected displays, reset PRAM, rebooted and cleared caches...nothin'."
We've notes from dozens of other readers who report the issue.
Shut lid immediately Since this problem generally occurs on notebooks with external displays, one workaround involves the following: Press the power button on your Mac (with external display connected) then immediately shut the lid. Your Mac will continue booting and the external display should show the proper resolutions.
Now, open your Mac's lid and go to System Preferences, then select "Displays" and press the "Detect Displays" button. You may now be able to boot normally with all previously available resolutions.
Reset SMC Instructions for:
MacBook and MacBook Pro
MacFixIt reader Philip Chadwick writes:
"An SMC reset solved the problem on my MBP 2.4GHz."
"I use a Samsung Syncmaster 191t as a desktop expander to my MacBook Pro. Two days ago, I used my MacBook Pro to drive a projector, and when I reconnected the Samsung, the screen resolution for the Samsung, 1280x1024, was missing from the list. Spent an hour and $50 with Apple support. After a PRAM reboot (?) and lots of time with disk utility, it is finally working again..."
To reset PRAM/NVRAM, shut down your Mac, then start it back up while immediately holding the following keys: Command, Option, P and R. Hold the keys down until the computer restarts and you hear the startup sound for the third time.
Delete a specific cache We've also received word that deleting the following, specific cache file:
can resolve this issue. [Thanks Fredrik]
Downgrading to Mac OS X 10.5.1 or removing the Graphics update If this issue proves too disruptive to your workflow, follow our tutorial on reinstalling the system then update to Mac OS X 10.5.1. We've received some reports that upgrading to 10.5.2 but refraining from installing the Leopard Graphics Update alleviates this issue, indicating that the graphics update is to blame.
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