The new computers (like all new computers that Apple has ever produced) come with a special build of MacOS X. This version is the only one that works on those computers at the time they are released, and it is only certified to work on the computers that it ships with (they usually work on other computers, but that should not be depended on). So a generic build not working on those computers is completely expected.

There ultimate solution is to wait until the next “dot-release” of MacOS X (at the moment it should be 10.6.4), at which point apple has (almost) always put the machine-specific components for new hardware into the (combo) update. Then you would make the next image with the 10.6.4 Combo update and all would be well with the world (until the next round of new hardware).

In the mean time you have two options:

1) Make an image specifically for those new computers, and make it on one of those new computers using the disk that came with them as your source DVD. I would really caution against using this image on any other models, but it might work fine (I always worry about hidden problem like the fans not working correctly for a given motherboard).

2) Use your normal image, but before allowing that image to boot (unsuccessfully as you have seen), boot from the installer DVD that came with the computer. The run it through an upgrade install, and you should have a working computer that (mostly) conforms to your image.

The latter solution is better if we are only talking about a few computers, and the former is better if we are talking about a lot of new computers.