Some MacBook Pro users who upgraded to the Leopard operating system are reporting that their notebooks' keyboards and trackpads have stopped working, according to Apple's support forums. The only apparent solution: Reboot the machine.

Messages posted in both the MacBook Pro and Leopard forums describe the keyboard problem as cropping up only after moves to Mac OS X 10.5, and they say that the fault is intermittent. "The keyboard will stop working and become unresponsive – the caps and number lock lights won't even turn on," said a user identified as Cub man. "Then after a few minutes, it turns on again and is fine until I let it sit for a while."

Other users, including Stefan Arentz, wrote of nearly identical symptoms. "This is on a MacBook Pro that I bought about a month ago. Now with Leopard the keyboard and trackpad stop working at completely at unpredictable moments. The only thing that helps is to connect an external keyboard/mouse and reboot."

And from kenji: "Zero issues whatsoever until installing 10.5. Now, keyboard disappears frequently and intermittently. I would have finished typing this post sooner, but my keyboard was unresponsive every time I opened a new window."

Apple support personnel do not participate in the forums, and other users, while sympathetic, had no definitive answers. Some of the affected MacBook Pro owners added that their keyboards became unresponsive most often after the notebook was activated from a sleep state, while others described the problem as if the keyboard itself had dozed off.

"Keyboard seems to go to sleep after a few moments of inactivity, wakes up if I hold down a key for a few seconds," said jonsef on the Leopard thread. "Extremely annoying! I have a new MB Pro, Leopard has been installed for about a week."

Apple-specific blogs and sites, have recently reported that the first Leopard update has been seeded to testers and may be unveiled soon. There is no reliable list of the fixes that might be included in the 10.5.1 update, however, nor is there a timetable for its release.

The MacBook keyboard problem is only the latest in a series of Leopard upgrade glitches that have included problems with Time Machine and difficulty making and maintaining a connection to wireless networks.