What does atitray.sys do? After much hesitation I disabled and uninstalled it (checked hidden devices in device manager, its gone) and all seems to work fine.
having the same puzzle too. there is an atitray64.sys error occurs on my new Vista64 system after installing ATT by the way, i think the ATi driver really sucks. the catalyst 8.9~9.3 ruined my afternoon today, the drivers seem to be not installed after installation that my new Vista64 reported that "can't find xxx drivers" or the ATT said "can not find ati video board or drivers". so i think ati really sucks