As I write this, I'm plugging in a 4th erupter into one of the dlinks and... zombie. Surprisingly, that only look less than 1 minute to happen.
I had a similar issue too. I had 5 Rosewill 5 port hubs with 4 erupters each running perfectly stable. Then I got 3 Anker 9+1 hubs and added my remaining Erupters and ran into the same symptoms.
In another thread Trongersol suggested daisy chaining the problem Hubs off of reliable hubs, more or less. So I plugged my Ankers into the Rosewills and all is stable once again.
I'm not quite sure why, I it may be related to impermanence mismatch or organization of devices behind controllers, dunno, but my setup is stable again.
Sam