Hmm, I'm not really sure what could be the issue there. What happens if you:
plug the Espruino board in
leave it for a while
connect with the Web IDE
Use up-arrow to step through the previous commands sent to the Espruino
Are there any AT... commands there? If so, it could be Windows is trying to connect to your Espruino as if it were a modem - it'd explain why it suddenly stops responsing if Windows just grabs control of the serial device.
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Hmm, I'm not really sure what could be the issue there. What happens if you:
Are there any
AT...
commands there? If so, it could be Windows is trying to connect to your Espruino as if it were a modem - it'd explain why it suddenly stops responsing if Windows just grabs control of the serial device.