Ive been seeing similar results with a test image im creating. I have a variety of t4** laptops with a HII image. It will deploy no problem to some, others it does what your desciribing. The best ive been able to do is to create a new OSD using the same info and setup a second item in the PXE menu. This has worked about 60% of the time. Let me know if we can compare anything else to figure this out.
Currently running 9.5 sp1