Just a heads up to all using (at least) the Tascam US-144 on Windows XP running Foobar2000 along with Executive Software Diskeeper 2009.
I was getting 'pausing' while playing back on either the spdif or analog ports on my Tascam. By pausing, I mean that the audio would cut in and out for about a second, on average once every 30 seconds, soooo annoying.
A restart would fix it, but I'm using my playback computer as a HTPC, server, and anything else I can throw at it, meaning that restarts take time (and possibly kick users logged into the server).
So I chased and pinpointed this particular problem, right down to Diskeeper 2009. If 'auto-protect' is currently on, diskeeper is constantly trying to defragment drives, which causes this pausing to occur. This happens even if diskeeper is trying to defrag a drive that's not the OS and not where your files reside... pretty strange...
But the fix is easy: just schedule 'auto-protect' on diskeeper to only be running at night when you're sleeping, on all drives. This will keep diskeeper from showing up as using active resources (in task manager) during the day, and in turn keep these irritating 'pauses' from occurring when you're listening to music during the day.
Also, on other 'pausing' issues: I've also had 'rf interference' cause sound to cut in and out while playing. When I turned a fan (with a speed setting control) on and off, or turned flourescent lights on and off in my living room, my sound would cut in and out, even while running the PC on battery power (meaning that this was not a power spike issue). I narrowed this one down to rf interference, interfering not with the wire, but with the sound card in the computer (i guess the wavelength was just right to resonate). Verrrry strange, but this problem appears to occur only for crappy on-board spdif asus soundcards, so all should be good that are using an external usb soundcard (like the tascam us-144)

Hope this helps some,
-Clayton