Loop Browser Glitches and Weird Waveforms

Loops play (and sync) ok in media players and once imported to the project.

However, in loop/ media browser preview about 2/3 of the loops work ok, but about 1/3 makes these awful noise bursts and often also show no waveform in LB/MB preview.

Ideas what’s going on and how to fix this?

Thanks in advance.

Hmm… It’s a brand new USB3 3Tb hard drive with some newly downloaded looploft loops. I’ve no idea what’s happening… The rest of the external hard drives are FireWire, I’ve not observed anything like this with them.