Some owners of 15- and 17-inch 2011 MacBook Pros are reporting issues with their laptops crashing when performing processor- or GPU- intensive tasks.
The problem happens when the load on the MacBook Pro's processor or discrete GPU unit suddenly increases. The crash is more of a freeze; the mouse pointer is still usable, but no applications, including the Finder, respond to user input. At that point, users must power off the MacBook Pro to regain control.
Many individuals are reporting via this Apple support discussion thread that their MacBook Pro fans rev up just before the freeze occurs. The information in the long and still growing thread seems to point to an issue with the discrete AMD Radeon GPU, or perhaps an interaction between the GPU and the new Sandy Bridge-based processors.
Apple is aware of the problem, and in some cases has provided replacement MacBook Pros to affected users.
If this is a driver issue, it can be corrected with a software/firmware update, so we'll be watching Apple to see what the official fix will be.
In the meantime, if you have experienced this issue, leave a comment here and let us know. Be sure to include the MacBooK Pro model, and what you were doing when the freeze occurred.