2012-07-25, 16:50
Are you using an Arduino board ?
Try to reinstall FTDI drivers : http://arduino.cc/en/Guide/Windows#toc4
or try with /dev/ttyS2 instead of /dev/com3
Try to reinstall FTDI drivers : http://arduino.cc/en/Guide/Windows#toc4
or try with /dev/ttyS2 instead of /dev/com3