I was running the stick for a while without any problem, but recently all of a sudden the bfgminer log started to look like this:

 [2018-01-10 19:41:27] Accepted 005114ba MLD 0  Diff 12m/7m
 [2018-01-10 19:41:33] Accepted 002be7f3 MLD 0  Diff 22m/7m
 [2018-01-10 19:41:48] MLD 0: ASIC has stopped hashing, attempting to restart
 [2018-01-10 19:41:49] Accepted 0038776b MLD 0  Diff 17m/7m
 [2018-01-10 19:41:50] New best share: 73m
 [2018-01-10 19:41:51] Accepted 000d96a3 MLD 0  Diff 73m/7m
 [2018-01-10 19:41:51] New best share: 115m
 [2018-01-10 19:41:52] Accepted 0008abcc MLD 0  Diff 115m/7m
 [2018-01-10 19:41:56] Accepted 002f34f2 MLD 0  Diff 21m/7m
 [2018-01-10 19:41:57] Accepted 006701af MLD 0  Diff 9m/7m
 [2018-01-10 19:42:16] Accepted 0045588e MLD 0  Diff 14m/7m
 [2018-01-10 19:42:17] Accepted 00256d79 ZUS 0aq Diff 26m/7m
 [2018-01-10 19:42:17] MLD 0: Unrecognized response
 [2018-01-10 19:42:19] Accepted 00798f2c ZUS 0bs Diff 8m/7m
 [2018-01-10 19:42:29] MLD 0: ASIC has stopped hashing, attempting to restart
 [2018-01-10 19:42:32] New block: ...a64ee3d1e95b8290 diff 3.66M (26.21T)
 [2018-01-10 19:42:32] Stratum from pool 0 detected new block
 [2018-01-10 19:42:42] Accepted 00592a2d MLD 0  Diff 11m/7m
 [2018-01-10 19:42:43] Accepted 00180ccc ZUS 0bk Diff 41m/7m
 [2018-01-10 19:42:47] Accepted 006127ac MLD 0  Diff 10m/7m
 [2018-01-10 19:42:53] Accepted 005c4df2 MLD 0  Diff 10m/7m
 [2018-01-10 19:42:55] MLD 0: Unrecognized response

etc

So it still hashes, but with frequent errors and at degraded hash rate.

All settings are default, I never overclocked the miner. No configuration changes (which I know about) were made. Powered USB hub.

What could it be?