I've posted about this problem before (it's proving *very* difficult to pin down the cause of the problem!) but I thought I'd ask again. Basically, my FF UC is occasionally recording small digital glitches to my Macbook Pro. It does it even when I'm recording a simple stereo arrangement and the buffer size is set to 512 samples, which is obviously ridiculous on a newish Mac running OS X 10.6. I use Reaper, but the problem used to happen in Harrison Mixbus, and on my old Mackie Onyx firewire interface too. It doesn't do it if I monitor in TotalMix so I know the problem is somewhere in the storage of data.

I've tried closing all other open programmes, turning off airport, updating firmware/drivers etc. but to no avail. I then thought, perhaps it's the internal harddrive that's faulty and not quite keeping up, so I've moved to recording to an external USB harddrive. However, it did the same thing on a live recording the other day (which is almost impossible to mend!). I want to check I'm doing this right: I have Reaper installed on my Mac HD, but I saved a new RRP file to the external harddrive so all files were recorded there instead. Is that the optimum way to record?

Even things like Youtube and, more recently, mp3s in iTunes (!) have been slightly glitching (i.e. a split second silence). Am I right in assuming that all this points to a faulty harddrive or RAM, or could it be something to do with the UC e.g. its USB cable?