The new Leopard operating system is locking up the keyboards of some MacBook Pro laptops, according to some users. The only apparent solution is to reboot the computer.

Messages posted in Apple's support forums claim the keyboard problem crops up only after moves to Mac OS X 10.5, and they say that it's intermittent. "The keyboard will stop working and become unresponsive - the caps and num 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 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 users said that their keyboards became unresponsive most often after the notebook woke 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. "Extremely annoying! I have a new MB Pro, Leopard has been installed for about a week."

Apple-specific blogs and websites, including MacRumors and AppleInsider, 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.