FTDI Reset Pin

Does anyone know why the reset pin on the FTDI chip (USB to RS232) is either pulled to +5V directly or through a RC circuit on arduino board designs? The FTDI documentation does not say this is required but it seems to cause intermittent serial communications problems if I disconnect the pin and just let it float. The problems show up just after installing the drivers on a Windows XP machine and may or may not come back on subsequent installations of the same device (disconnect/reconnect USB cable to PC).

Are you referring to pin 19 (RESET#) or pin 2 (DTR#) on the FTDI chip?

Pin 19 (RESET#)

if I disconnect the pin and just let it float

Why?