I'd say double check the same thing Major said. make sure in the BIOS that the ps/2 port is enabled.
other than that, since you did
say the ram was new, try putting the old ram back in and see if you get the same problem and windows isnt freezing or something at logon.
also make sure usb is enabled in the BIOS and try plugging in your wireless combo at the logon and see if you get an hourglass like its detecting it and wait a tad.
other than all that im stumped.
hope that helped some