MOD-WiFi-ESP8266-DEV persistent errors

[squishyheadboy]

I'm using the MOD-WIFI-ESP8266-DEV board with the ESP8266-EVB carrier.  I'm trying to program it using the arduino 1.6.1 software, as in the video at the olimex blog (https://olimex.wordpress.com/2015/03/31/programming-esp8266-evb-with-arduino-ide/).  The same process works perfectly for me with other esp8266 modules, but not with the Olimex ones.

I can connect via serial from my PC to the board.  When I reboot the board, a serial terminal shows the usual few bytes of random junk, then "Ready", as might be expected.  Immediately after that, though, the board sends the single word "Error" over and over again (even though no data is being sent to the board).  The board does not respond to any commands sent from the PC.  If I reboot the board into bootloader mode, it does not send the "Error" string, but nor does it respond to reprogramming.  I have tried this with two different Olimex modules, and get the same responses from both.  I have tried with and without the carrier board.

Am I just unlucky to have two faulty modules, or am I doing something wrong?