I meant the yellowjacket nanofury nf1s, I had issues where I have the miners disconnect and then replugged back in (I'll see if I can get a screen shot of the error line, right now the line cgminer posts was somewhere about "attempted reset got err (0): LIBUSB_SUCCESS). I also noticed as part of my problem is that cgminer doesn't show any hardware errors at all. After a day of mining the amount of errors it shows was 0.
Temporary instability would cause the nanofuries to stop working. Cgminer intentionally resets them and hotplugs them again to try to get them going again. Different hardware is more or less susceptible to this happening and I remember having the same issue with NF1s until they eventually died completely and started causing spikes and shorts on my usb hub and I had to throw them out one by one (I now have none). Because the nanofuries use the bitfury chips which have a hardware error rate in their design of about 15% it makes it difficult to gleam any useful information from the hardware error rate so I never bothered to even count them, hence it will always read zero for that particular device.