[Rich Breen]

A few other thoughts;

While those G-Tech drives are generally quite good, I bought a few last year which acted up (going to sleep after a while even with sleep off, etc), and upon opening them up I was surprised to see they were green drives inside (drives with power saving features) - they're not supposed to be. I returned them. I would consider trying a different drive; a WD Black is what you want. I have never had issues with drives from OWC or Glyph and would recommend those if you can't specify the make/model of internal drive from your vendor.

While I agree that for best performance, Spotlight *may* be an issue, I have only ever seen it cause momentary issues on large multitrack recording. Personally I keep Spotlight on all of my drives and never have problems, but I would disable it on a system dedicated to large multitrack recording (i.e. in a large tracking studio). You can drag the drive to the "Privacy" pane in the Spotlight prefs pane and it will no longer be indexed. Be aware that this may cause performance issues in the workspace browser.

Seems this is clearly drive-related, so I'd change out the drive to something reliable and see how things progress.

best,
rich