Interesting problem. I had this with 6.5 and when we applied SP1 it
went away. It just started up again with SP2.

Here's an example. Boot an HP NC 6220 (or any other machine). Hit F12
for network boot. It used to look at the rules and image the machine.
Now it says no work to do.

If I do a manual boot, type img and then hit F9 which is look for work,
it images.