Apple has released MacBook Pro SMC Firmware Update 1.5: it fixes an issue where the machine would shut off unexpectedly under heavy processor load, even when plugged in. As I actually had some issues before, this update is very welcome.
This update resolves an issue where a MacBook Pro being used with a power adapter may unexpectedly shut down under heavy workload if the battery charge level is near empty.
Your computer's power cord must be connected and plugged into a working power source, or your battery must be at least 25% charged.
When your computer restarts a gray screen will appear with a status bar to indicate the progress of the update.
Your computer's fans will run at full speed during the update but will return to normal speed once the update completes.
Do not disturb or shut off the power on your computer during this update.
The MacBook Pro SMC Firmware Update 1.5 can be downloaded from Apple's support website.