Hi, For anyone that's interested, I have determined that using OS X 10.6.8 and its companion Xcode version (3.2.6), no OS X version 10.6.x build succeeds (error 2). Using OS X 10.6.3 and its companion Xcode (3.2) it is possible to build any 10.6.x OS X version except 10.6.8. I know that this is not a tight bounding of the problem, but it's what I have. Luckily for me building 10.6.7 in a 10.6.3 environment is sufficient for my present needs. David Lee