THe serial port driver, and something else called "PCI Simple Communications Controller" (possibly a modem on the motherboard) are listed as "other devices" in the device manager, with yellow exclamation marks in the icons meaning they have no drivers installed.
Dell does not list any drivers on their usual website where you enter your service tag. I am pretty sure this is a standard Intel Q## chipset. Does anybody know which one exactly, and where I can get the chipset drivers and particularly, the serial port drivers, for 64 bit Windows 7?
1) Install the latest chipset drivers from dell's site.2) If that doesn't work, install the latest networking drivers from dell's site.3) If that doesn't work, install the latest video card drivers from dell's site.
Go to Dell's support site and look up 745C drivers under "Chipset". Download the last 2 drivers and install them in your Dell driver directory under Intel PCI Driver Management. Use these to update the drivers in the Device Manager and problem fixed! 2b1af7f3a8