That sounds like a hub not supplying enough power.  What hub(s) are you using and what is the current and voltage rating of the Power Supplies.

Sam

The hubs are DLink DUB-H7 7-port hubs, with 5 sticks in each hub with 3A power supplies.  It's my understanding that each BE should use 0.5A, so this should provide sufficient overhead for 5 sticks.  These hubs are well-known to work well with BEs in groups of 5.

Most importantly though, they work flawlessly when attached to a Linux box running different S/W, so I think blaming the hardware is probably a dead-end.

No it was not always the same erupter or port or hub.  It seemed to be completely random.  Even the erupters plugged into the 1.2A fast-charge ports had the issue randomly, with the same frequency as the sticks in the normal ports.

I was only using one instance of CGMiner, and the only options on the command line were '-G' to avoid using the GPU, and -c to load the correct config file.

...
I installed the Windows binary distribution of CGMiner - 3.3.1, I believe, was the current release at that time.  I read the README, and downloaded the Zadig binary linked on page 1, and installed the WinUSB driver for my block erupters, and for my BFL devices.  I then (just to be careful) rebooted the PC.  All devices appeared to be using the correct WinUSB drivers, so I then started CGMiner.  The devices were all recognized, and seemed to function as expected.  Over the next few days, however, I found that at least one Block Erupter would stop working after, on average, ~2-3 hours.  CGMiner would be constantly printing a communications error with the failed device, and the device itself would have an LED that was fully on constantly.  Manually unplugging and re-plugging the device would fix the problem, and CGMiner would autodetect the newly-reinserted device.

So what did I do wrong?  I did not try CGMiner under Linux, but whether or not that works would not change the fact that there was a problem with the Win 7 configuration, and that is the problem I reported.

So which is it?
Wrong version? Wrong libusb.dll? You built it yourself and didn't follow the libusb instructions?
... and cgminer will be rock solid on linux also if you do it as per instructions.

3.4.0 works great on RPi and BE, and arch is a better choice.

Thanks, I will try to set it up. I did have a look already in Kano website. How do I add an auto start cgminer when power up the rpi and load a config?