My 575CT is in a Dell Latitude. I have installed the beta possible fix issued late May but it seems to make no difference. Whenever the system is rebooted, the adapter appears to be unable to send. If I crank up a ping after a few failures I get the old faithful "Transmit ring full .. refusing to send" message. Oddly enough, it is normally the case that as soon is that message is issued, it does begin to send. Once it does begin to send I encounter no problems until the next reboot... As you might suspect it works 100% reliably w/ Win98.