Click track sporadic glitches

Click track fine in 1 song, not another

Mysterioso!

To keep it simple …

I’ve got 2 skeleton songs built from the same “template” I’ve successfully used before. All I want to do right now is record the metronome as a click track through a drum machine via MIDI. [This in N version 6.0 using ASIO drives and an M-audio soundcard].

I’m sure I didn’t have this problem a week ago, but today I find that on the one song the .wav of the metronome records fine, while in the other song it records with sporadic distortion (almost a pattern of a glitch every 5 beats).

Question 1: Surely this can have nothing to do with buffering? With ASIO drivers that’s set by the soundcard, so if it works with one song, it should with them all - right? No settings in N-Track can affect that, can they?

Question 2: As far as I can see, my recording settings in both songs are identical. So what is it that’s making the response to audio inputs different between the 2 songs? Any suggestions?

(Further infomation: the metronome’s input is through the “Audio In” of the soundcard. I actually believe I get the same “differential distortion” problem between the 2 songs with guitar/vocals through the SPDIF inputs)