slow playback

[muscmp]

i'm using a mac g4 with pro tools 5.0LE. i recently upgraded to os9.2.2 and everything has been working fine.
usually about once a month, even with os9.04, when i playback my songs, they play back real slow. i'm usually able to eliminate this by trashing any and all sound preferences in the system/preferences folder. this time no luck.
i've tried rebooting but after 5 times it becomes worthless to attempt it any further. i could try eliminating all of the extensions; then re-enabling them but what a process.
has anyone had this happen to them?
also is it worthwhile to upgrade from 5.0 to 5.1? i'm so paranoid of upgrades that it took me a while just to go to 9.2.2
lastly, i want to dump my pro tools files to cd without having to bounce to disk. that way if i want to tweak a track, i can load it back up and do so. is this possible?
thanks in advance.