This behaviour looks familiar but I have another variant:
When zooming in in the last (means highest) level the waveform is a completely different like on another position and not disappearing. Its just annoying because the last working zoom level is okay for repairing spikes in the waveform… but it feels strange and unreliable of course every time doing that.
I think it is in fact system independent: My new computer does it like the old one (Win 7 x64 - before Win XP) and also a colleague suffer from the same phenomena.