Slipping cranks, drive chain slip?

^^^^ The lock rings that come with those hubs are really shit and have heard of lots breaking in just that way.

I use Paul and DA lock rings now and tighten them up just a little less than 'really fucking tight' and haven't had a problem.

Glad I'm not the only one they've broken on. Though it sucks they break.

Got the DA ring on tonight, been for a blast and seems solid now. Will consider changing the hub once I get some spare cash.

So basically generic shit isn't worth the metal it's forged out of?

Not in my experience :(