Frozen sleep update?

my G4 would not wake up from sleep often enough to be extremely annoying.
Salmon Egg wrote on :

Several months ago, I posted that my G4 would not wake up from sleep often enough to be extremely annoying. IIRC, the problem was exacerbated when I switched to Leopard. From various other postings, I knew that I was not the only to suffer such a fate. The same was occurring with G3, G5, and notebooks as well. This problem is what finally pushed me into getting a Mac Pro. That rewards Apple for producing bad software. I do report, however, that the Mac Pro running Leopard has been rock solid so far. It had a few annoying quirks, but they seem to be debugged as updates come out. The serious freezes and system crashes seem to be gone. For example, the worst I had was the fault of an application I was running, MT-NewsWatcher. Although the application failed, Leopard took the failure in stride. An updated beta version of the application is good enough.

That said, I still have problems with my old G4. From time to time, as I am still trying to transfer files from the G4, I still freeze in sleep. This is particularly troublesome because I am using a USB drive to transfer data. When I have to hold the power button down to break out of sleep, the drive does not get dismount properly as it would during a properly powered shutdown.

Has there been any announcement as to why the freezes occur and how to prevent them or recover from them? Has anyone else had such freezes lately, especially on a Mac Pro? Is the problem not occurring on Mac Pros?