This sure looks strange but, peering closely, I think the weirdness is actually an artifact of the screendraw algorithm. I'm not familiar with "CD wave", but what seems to be happening is that, rather than drawing a single point for each sample, it's drawing a line & "filling in" between the sample and zero, kind of like a bar chart. So every sample point above zero becomes a solid bar from zero up, and every point below zero becomes a solid bar below.
What gives this away is the perfectly flat edges at the zero point. Also, the fact that, if you imagine the outline of the waveform, ignoring all the green fill-in. it actually looks ok. The problem we see here is probably just the result of looking closely at a quickly drawn waveform which is simply intended as a rough indication of what will be burned to the CDR.
So, even if you use the app quite often, you might not notice this anomaly until you start to zoom in (like your screenshot) I reckon that if you zoom right in, it might be easier to see exactly what's happening.
It's probably worth loading the file into another audio editor - Audacity, or anything you have kicking around, just to see what that makes of it, though.
BTW, I think your "hum" issue is completely separate, more likely to be connector/ ground related as has been suggested already.
It's intriguing though...