Hi, I have this peculiar problem only with Premiere Pro CS4.
When setting the scratch disks on any drive other than the C drive, they always default back to the C drive.
This does not happen with CS3 or previous.
Premiere creates directories on the selected drive (other than C) but it dumps the preview files back on C, while the newly created directories remain empty.
This happens both on AMD and Intel machines, on windows vista ultimate.