I have a Powerbook G4 17" and I recently updated to the Mac OS 10.5.8 and got a monitor. I put it to sleep by closing the lid and sometimes it resumes normally and sometimes it doesn't. It doesn't matter if it's on sleep for a day or 10 minutes, it just happens randomly. It wakes up, but the screen doesn't flash blue for a few seconds like it normally would, indicating that it found the second monitor. It just wakes up, and a picture appears on both screens and the mouse moves, but nothing responds. The only way I can make it work again is by holding down the power button until it shuts down and then turning it on again. this frustrating because then I have to reopen all my programs and Safari tabs. I tried resetting the PMU by unplugging everything and taking out the batter, then holding the power button for five seconds, but it has the same problem no matter what I do.