I would suggest that you do an Archive and Install on that puppy and see if a new system will fix its problem.
It may even sort out your email problem.
Use the installation disks, or the restore disks, to perform the Archive and Install. All your date will be preserved, but back it up anyway.
That machine will take 10.4 easily and give you more flexibility.
10.3.9 G4 wakes up in the middle of the night & is running for hours. I have ProTools but haven't used it recently.