disk too slow error message

[jerkcrap]

This is soooo annoying. I (way too often) get an error message that says that my disk is either fragmented or too slow. It prevents me from successfully recording many times. Two days ago I maxed my RAM and got a 120 gig firewire hard drive with an 8 meg buffer. I saved copies of my sessions to this new drive and got the same errror message although less often. This is unacceptable.
Would it help to defrag the partition with the program, plugins and system software?
Any other recommendations?
Jake
Titanium G4 800, 1 gig RAM, MBox, 60 gig internal hard drive 2 partitions (1 10 gig w/ software installed/50 w/ files stored), 120 gig/8 meg buffer firewire hard drive 3 equal partitions