Changing Wavetable Frequency ends in corruption

[catvvvveasel]

I'm making waveforms for display on an oscilloscope, I get some cool stuff happening by wanging the frequency around :) However after a while it breaks and the wave is corrupted, it becomes steppy and scrambled. Its similar but worse to what happens if you hit 0, I've set it to a minimum of 1 now, but after some time it still happens. I have to delete the node and undo to get it working again. It looks kind of cool though ;)

I've just had it switching with a linear filter from 2 to 600hz, after a few changes it broke, then broke again a few more times, then eventually, unbroke then carried on in the same fashion, eventually it breaks completely...