I have 11 mld2s, all on one hub. No problems, until yesterday. Now one MLD isn't well recognised by the hub anymore (irrespective of the USB port I put it on): sometimes it does not show up in windows COM drivers (and I get error message 'unrecognised device' or something like that), sometimes it does but it refuses to communicate (the yellow light maybe flashes once but that's it, and it does not show as a MLD device in bfgminer). First I thought the USB chip on the MLD was semi-fried for some strange reason.

Now, when I plug that same device in a USB port directly on my PC (same PC as the hub with the remaining 10 MLDs is connected to), it works fine, it is properly recognized by windows and hashes away just fine. I have tried powering my hub on/off etc, but didn't help. It drives me nuts. So I guess it is something in the hub, but it can then only the hub controller because the power and the individual usb ports are fine by themselves. It's a 19 port Eyeboot hub, I think jstephanop also said that eyeboot hubs are not the greatest (when stretched).