SerialPort.GetPortNames()

Hi all. I'm using this seemingly simple code (from msdn) to fill a combobox with available Com ports but it keeps adding this strange character at the end of it, like so "COM4?"

It was working fine yesterday, but it started doing it after a reboot and no change to the code.

foreach (string s in System.IO.Ports.SerialPort.GetPortNames())
Combobox1.Items.Add(s);