Well, that is a check_if_mount. I do not think that should have been a problem... So, even with fidsift (and hijack?) you are still seeing problems. Do you see any other evidence of disk problems during playback? Also, are you running any other third party software from one of your filesystems - sometimes, if a file is open or busy it will not allow a sync because it cannot unmount / remount the filesystems. Something to check...