My most recent normal 3.8.4 test ran about 12 hours without incident - no zombies at all. I've just run the "sw" test and it has one zombie after about an hour, AMU5.
Edit: another zombie with the "sw" test, about 5 hours into the run. Curiously, this one was also reported as AMU5 although it wasn't the same physical device as above. Unplugging it did not change its status to AMU0, unlike many of the earlier versions. On replug it was reallocated to AMU14 and the numbering overall suggests it had actually been AMU7 that went zombie this time. Present numbering is AMU0-4, 6, 8-14 so I think the first zombie, AMU5, was reallocated to AMU13 on replug. The "sw" run continues.
I found an Amazon (Canada) listing for the hubs I'm using, fwiw:
http://www.amazon.ca/gp/product/B009Z9M3DYI just noticed this phrase in the blurb for them "Smart chip power management allows devices to communicate idle states and latency tolerance for progressively lower power states and subsequently increased performance and power efficiency". Don't know if it's relevant.
I am running 3 10-port Anker hubs and an old 4-port hub, all individually powered and plugged directly into the PC. No daisy-chaining. Interestingly I don't remember ever seeing one of the 4-port devices going zombie...
So... On an initial test of "sw" without logging, I noticed some LEDs come on for several seconds then go out, and mining continued OK. Another time a zombie was reported but it re-plugged automatically. Then several zombies came up which did not re-plug automatically and I noticed "icarus detect - incorrect device" warnings. I don't know if these are new with this build or not, but when they came up I did examine the whole table in Zadig to check if AMUs had been re-assigned to slots with incorrect driver software - but they all looked OK.
Powered the hubs off/on to reset everything as usual.
On this run (with logging), a zombie (AMU 22) appeared after about a minute, which did not re-plug automatically. Manual re-plugging worked OK, but I stopped the test because I was going out and wanted to be sure
the miner would keep running. It seems that this version tries hard to keep things going, but I seem to be seeing more initial disturbances (LEDs on for a second or more then disappearing, then maybe a zombie which replugs automatically etc.) I don't see any of that with 3.5.1, and as I'm normally sitting right next to the Erupters working away at the PC, any unusual flashing immediately catches the eye.
Logfile here, for what it's worth:
https://dl.dropboxusercontent.com/u/44240170/logfile-sw.txt