C# SerialPort - Receiving extra 255 bytes

Thanks Ray. Could you please take a look at the last thing here:
I have found something... really stupid. You said that you have discovered that opening the serial over USB in effect resets your Nano. Well... During investigation of my issue I have found that setting

serial.DtrEnable = true;

Prevents C# from sending unnecessary 255s but instead it resets my DUO every time I call

serial.Open();

What an annoying thing...

I’m going on holidays. I will get back to you guys on Monday.

Thanks for your help and time!