Do you see a message just before one of them goes zombie about any usb errors in particular?
I've downloaded the latest 3.6.6. cgminer-nogpu.exe but it still gives me a couple of zombies after 10 minutes and also continuous timeouts on another AMU which is NOT one of the zombies.
I've now restarted with a logfile - see below for the exact details.
Another thing I noticed, which may or may not be important:- When I first ran cgminer-nogpu after changing from 3.3.1, I didn't bother to power the hubs off/on, and when cgminer-nogpu started up it turned off all the green LEDs on all 34 erupters - i.e. it found them all - but it was only showing 33 erupters (0-32). Cgwatcher was reporting 33 devices also. As far as I could see, shares were being processed from all the AMUs (green flashes) - so what happened to the missing device? I powered off/on after that and got all 34 devices working as normal. Not sure if it's important, but I thought it worth mentioning as I haven't seen this behaviour before, as cgwatcher has always reported the correct number of devices, even if they were not showing on the cgminer screen.
Ah, just about to post, and now I have errors and a logfile. Here's an extract:
[2013-10-27 10:59:29] Started cgminer 3.6.6
:
[2013-10-27 11:05:21] Accepted 0db97324 Diff 18/8 AMU 31 pool 0
:
[2013-10-27 11:05:59] AMU 31 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:05:59] AMU31: Comms error (werr=-7 amt=0)
[2013-10-27 11:06:00] AMU 31 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:06:00] AMU31: Comms error (werr=-7 amt=0)
[2013-10-27 11:06:01] AMU 31 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:06:01] AMU31: Comms error (werr=-7 amt=0)
[2013-10-27 11:06:02] AMU 31 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:06:02] AMU31: Comms error (werr=-7 amt=0)
[2013-10-27 11:06:03] AMU 31 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:06:03] AMU31: Comms error (werr=-7 amt=0)
[2013-10-27 11:06:04] AMU 31 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:06:04] AMU31: Comms error (werr=-7 amt=0)
[2013-10-27 11:06:05] AMU 31 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:06:05] AMU31: Comms error (werr=-7 amt=0)
[2013-10-27 11:06:05] Accepted 031d7613 Diff 82/8 AMU 20 pool 0
[2013-10-27 11:06:06] AMU 31 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:06:06] AMU31: Comms error (werr=-7 amt=0)
[2013-10-27 11:06:07] Accepted 1928fe55 Diff 10/8 AMU 5 pool 0
[2013-10-27 11:06:16] Stratum from pool 0 detected new block
[2013-10-27 11:06:16] Rejected 035c23e1 Diff 76/8 AMU 21 pool 0 (Job '84396' not found)
[2013-10-27 11:06:16] Rejected 0b03fc59 Diff 23/8 AMU 29 pool 0 (Job '84396' not found)
[2013-10-27 11:06:16] Accepted 0432dd08 Diff 60/8 AMU 19 pool 0
[2013-10-27 11:06:18] Accepted 1d3203f8 Diff 8/8 AMU 31 pool 0
:
[2013-10-27 11:10:59] Accepted 1772e531 Diff 10/8 AMU 13 pool 0
:
[2013-10-27 11:13:27] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:27] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:28] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:28] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:28] Accepted 0c9c1e70 Diff 20/8 AMU 28 pool 0
[2013-10-27 11:13:29] Accepted 057ce3b2 Diff 46/8 AMU 27 pool 0
[2013-10-27 11:13:29] Accepted 160bf5ea Diff 11/8 AMU 5 pool 0
[2013-10-27 11:13:29] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:29] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:30] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:30] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:31] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:31] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:31] Accepted 1bdbce81 Diff 9/8 AMU 18 pool 0
[2013-10-27 11:13:31] Accepted 1df086ca Diff 8/8 AMU 25 pool 0
[2013-10-27 11:13:32] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:32] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:33] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:33] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:34] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:34] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:34] Accepted 0db2ded2 Diff 18/8 AMU 21 pool 0
[2013-10-27 11:13:35] AMU 13 SendWork usb write err:(-7) LIBUSB_ERROR_TIMEOUT
[2013-10-27 11:13:35] AMU13: Comms error (werr=-7 amt=0)
[2013-10-27 11:13:36] Accepted 0ff4b00e Diff 16/8 AMU 14 pool 0
[2013-10-27 11:13:40] Accepted 0f865896 Diff 16/8 AMU 13 pool 0
:
[2013-10-27 11:13:55] Accepted 19b8a6cd Diff 9/8 AMU 13 pool 0
:
[2013-10-27 11:14:22] AMU 13 SendWork usb write err:(-4) LIBUSB_ERROR_NO_DEVICE
[2013-10-27 11:14:22] AMU13: Comms error (werr=-4 amt=0)
[2013-10-27 11:14:22] AMU 13 failure, disabling!
[2013-10-27 11:14:22] Thread 13 being disabled
:
[2013-10-27 11:14:30] Icarus detect (5:34) failed to initialise (incorrect device?)
The full log is here:
https://dl.dropboxusercontent.com/u/44240170/logfile.txtDoes it help?