My guess is that a change to the OS has caused a bug in PageMaker to become apparent. Report the problem to Adobe and Apple, and keep an eye peeled for PageMaker updates. The problem you're experiencing may be limited to certain Mac models too.
For what it's worth: Prior to 10.2.5, Classic had this same problem, on some PowerBooks. It was fixed in 10.2.5.
In general, each rev of MacOS X seems to bring about different sleep related issues, particularly for older PowerBooks, which have been having sleep related issues since day one. Just be thankful you don't have to deal with the coma sleep problem (leading to system crashes upon sleep, or wake-up).