MacFixIt recently posted a few tips on how to take full advantage of the built-in screen shot functions. For several MacBook Pro users, specifically owners of the newer "unibody" models, the screenshot functions cause problems wherein the computer will freeze up for a few minutes.
Apple Discussions poster ikarus79m writes:
"I have noticed a super weird bug with my new MacBook Pro. At least while running the integrated graphics chipset (not yet tried in power mode.) When I snap a screenshot using Shift Command 3 (or 4) my computer takes the screen grab, however, then freezes for a minute or two. After that it comes back to life."
There are several potential causes for this problem. The first could be a driver problem, where the screen shot utility is more prone to problematic behavior when running with the drivers for the newer computers. This may be supported by some users having the problem only when running on the GeForce 9400M GPU.
There are several things users have tried which have helped the situation.
Repair permissions This problem seems to be influenced by some permissions problems for core system files. Fixing permissions using Disk Utility seems to help the problem. Alternative to Disk Utility, users might wish to do a more in-depth system cleaning using a third-party utility such as AppleJack or OnyX. These utilities can fix multiple problems beyond just permissions, since they can clear many caches, run built-in maintenance scripts, and run a variety of other tasks to keep the computer running optimally.
Reset the SMC and PRAM While it's unlikely that hardware settings in the SMC and PRAM would directly affect the screen shot utility, some users have seen improvement after resetting them. It is possible that some faulty setting could interfere with driver function. To reset the PRAM, hold the options-command-P-R keys down all at once after restarting, allowing the computer to reset s couple of times before releasing the keys and allowing the computer to boot normally. This Apple Knowledgebase article (http://support.apple.com/kb/HT1411) contains the steps for resetting the SMC on various MacBook models.
Workaround Because this problem is with the internal screencapture utility, users can bypass it by using a third-party screenshot utility. There are many out there, and users can search for one with the desired features at http://www.versiontracker.com. However, the following three are a couple of recommendations: