When you restart your computer, COM port setting revert to the default value?

You can change them in Device Manager or at the a command prompt, but they are not retains after a restart?

If you Open a CMD prompt and type MODE COM1:, you receive a display similar to:

Status for device COM1:                              -----------------------                                  Baud:            1200                                  Parity:          None                                  Data Bits:       7                                  Stop Bits:       1                                  Timeout:         OFF                                  XON/XOFF:        OFF                                  CTS handshaking: OFF                                  DSR handshaking: OFF                                  DSR sensitivity: OFF                                  DTR circuit:     ON                                  RTS circuit:     ON
In Microsoft Windows 2000, COM port settings for command functions are maintained only for the active Windows session. Custom settings are discarded at shutdown.

To workaround this feature, create a Minimized shortcut in your startup folder. If you wanted COM1 to be
Baud rate=9600; Parity=None; Data Bits=8; Stop Bits=1
set the shortcut target to:

C:\winnt\system32\mode.com com1: 9600,n,8,1