"This apparently happens when ESC's don't think the throttle is "off". I had one motor beeping on my hexacopter; it turns out that the ESC's are not "calibrated" the same (and vary by temperature; only crystal controlled ESC's don't), and as…"
"I've had this happen several times when trying to load Arducopter firmware 2.9.1; after (4 or 5) attempts, successful load and verify was achieved. In the midst were a couple of reboots of the virtual machine. I'm running windows 7 home premium…"
"I ordered an ArduPilot board from SparkFun on March 11, and it came with the wrong fuse value in the AT45. I had to reflash with open-source avrdude (using tinyUSB programmer from Lady Ada). See bcr's comments on page 5 of:…"
"I ordered my ArduPilot on March 11 from SparkFun, and it arrived with the wrong divisor programmed into the AT45 (so the autopilot control input was not being processed properly; effectively ignored). Thank goodness for bcr's comment on Feb 22,…"