Those affected by the problems with sudden shutdowns on MacBooks will be pleased to hear that Apple has released a firmware update to stop the syndrome shutting down MacBooks.

"The MacBook SMC Firmware Update v1.1 improves the MacBook's internal monitoring system and addresses issues with unexpected shutdowns," Apple stated in a support article on its website. "This update is recommended for all MacBook systems, including those that received warranty repair."

The update is available via Software Updates but can also be downloaded manually from the Apple website.

"If your MacBook is running Mac OS X 10.4.6, you won't be able to see the SMC Update until you update to Mac OS X 10.4.8," Apple noted. "Once you have updated your system software, the SMC Update will appear as an option in Software Updates."

MacBook users running Mac OS X version 10.4.7 will be able to download and install the SMC Update, so it is not essential that users update their system software. However, Apple always recommends updating to the latest version of the system software.

Apple has long tried to work out what the cause of the problem with sudden shutdowns was. Affected users have had their MacBooks repaired many times without solving the problem.

The new firmware update indicates that Apple has isolated the problem and found a solution. But the company also states that if downloading the update still doesn't solve the problem, users should contact the AppleCare centre for further instructions. Anna Lagerkvist