For 52 Folk Songs I'm recording songs using Audacity (running on a Mac) and a Zoom H2 digital recorder. Some of the time I use the Zoom standalone and transfer the WAV files onto the Mac, but mostly I use the Zoom as a microphone, connected to the Mac (and powered) by a USB lead.

Just recently, the Zoom and/or Audacity started malfunctioning intermittently: it records what sounds like a massively overdriven & distorted version of what I'm singing/playing, at the right volume level but sounding like something out of Dr Who (and with blocky square waveforms).

I haven't been able to find any rhyme or reason as to why and when it does this, except that it doesn't go wrong while it's actually recording; it usually happens when I do one bit of recording, leave it for a while and then start recording again. It doesn't seem to be connected with listening back to the previous recording, as it's happened without my doing that. I can generally fix it by unplugging the Zoom and then re-establishing the connection - which is laborious, as it has to be done at both ends, the Zoom and Audacity - although sometimes I have to do this twice.

Anyone seen (or rather heard) anything like this? Any ideas?