How about the enabler software to allow the computer to run 8.6? Is there one as on earlier powerbooks and duos? If not, why the message? Dan in AZ Chuck Kenney wrote: I tried installing 8.6 on the 2400, rebooted, and it tells me that "this startup disk cannot be used with this computer". The drive was formatted startup disk cannot be used with this computer". The drive was formatted with 8.1 then I let the 8.6 installer update the driver.