We have a PC with NT4 and SP6a. The mouse is an MS ps2 w/serial connection. I have changed the mouse from serial to ps2 w/serial 3 times. There are no irq conflicts. I can't install driver because the "Change" button on the ControlPanel>Mouse>Properties>General tab is disabled, (greyed). The mouse name is "Unknown".<br>I reinstalled NT and SP6a, but it made no difference.<br>Any ideas?