I was doing a heavy mix in Nuendo today which was pushing my machine ( a dual Opteron 242 with 2gig of ram) quite a bit. Since I'm using an Emu 1820 (which is suprisingly good for the money and a great interface all around) it can switch latencies up to 100 ms (on average in a session I use a value between 5-12 ms dependent on the cpu load).
So, in this case I switched it to 100ms (the highest setting) to ensure no pops and clicks during playback.
Rmx went nuts.
Upon loading the session, one of the rmx channels that had an internal delay effect and phaser on it (bmp delay x2 and phaser) went in some sort of feedback loop causing a distortion marilyn manson would be proud of.
The only way to stop it was to remove the effects.
Next to that, there was a big zippering/clicking noise on playing back any loop.
Wondering whether this was due to the session itself, I created a clean session with one miditrack and RMX. The zippering I can reproduce, the feedback stuff not (sorry marilyn:P), although I can in the old session by just opening it up.
Anyhoo, to reproduce:
-you need an emu card, don't know about any other cards that will allow you to go to 100ms buffer size)
-open rmx, load a beat, play it.
-click, click, crunch, stutter...