Pronterface won't connect to RAMPS 1.4 (2 replies)

I have been having trouble getting Pronterface to connect to my RAMPS 1.4/Arduino Mega. When I try to connect, the monitor just says "connecting...", and when I unplug my board, I get the following error:

[ERROR] Can't read from printer (disconnected?) (SerialException): call to ClearCommError failed
[ERROR] Can't write to printer (disconnected?) (SerialException): WriteFile failed (WindowsError(22, 'The device does not recognize the command.'))
[ERROR] Can't read from printer (disconnected?) (SerialException): call to ClearCommError failed
[ERROR] Can't write to printer (disconnected?) (SerialException): WriteFile failed (WindowsError(22, 'The device does not recognize the command.'))
[ERROR] Can't read from printer (disconnected?) (SerialException): call to ClearCommError failed
[ERROR] Can't write to printer (disconnected?) (SerialException): WriteFile failed (WindowsError(22, 'The device does not recognize the command.'))
[ERROR] Can't read from printer (disconnected?) (SerialException): call to ClearCommError failed
[ERROR] Can't write to printer (disconnected?) (SerialException): WriteFile failed (WindowsError(22, 'The device does not recognize the command.'))
[ERROR] Aborting connection attempt after 4 failed writes.
[ERROR] Can't read from printer (disconnected?) (SerialException): call to ClearCommError failed

I have made sure that Pronterface and Marlin are using the same baudrate and serial port, and that the Arduino IDE is closed when I try to connect.
I have bought a brand new Arduino and Ramps board, still doesn't work.

Here is my config:
https://pastebin.com/zDemtR2B