I am now also having a similar problem, the printer has been working fine for about a month, last night about an hour before the end of a 5 hour print I noticed the Pronterface was disconnected. the printer was still printing from the SD card though. When I tried to reconnect it said " can't connect to port COM7, Access is denied" now I have to reset the computer and the printer. I then start pronterface back up it works fine for a minute or two if it disconnects in the middle of homing it freezes if not it just looses connection and comes up " can't connect to port COM7, Access is denied" this is really annoying everything was working fine before and I do not understand what could have changed. When I put the board to USB mode it seems to connect fine even if that error has been coming up before switching to USB.
My Reprap is a Tri-colour Mendel.
My Reprap is a Tri-colour Mendel.