I have a few installation packages that wont install, (only on the XP SP2 wrkstations). The few WIindows 2000 and XP sp1, (worstations are fine.) Updated to the latest windows installer, tripled checked to see if any domain policies might be responsible. I am using the default users and computer OU, (with only the default domain GPO which has nothing enabled). Dropping it down to a work group will resolve my problem. Found a technet article, add regkey DisableMSI being one, (didnt work).