As large swathes of the background are often also black this makes it pretty tricky to discern the actual waveform

I've experienced this problem in both WMP11 and RealPlayer, running Vista Home Premium. I've just reinstalled 5.2b1 and the colours are back, so it looks like this is only an issue in the latest beta.
Anyone else got the same issue, or is it somehow specific to my setup?
Thanks muchly and happy new year to all.