UFD booting issue on some hardware...

I've noticed with the latest release of WinBuilder (v49), that some machines will not boot off the created usb flash drive.  So far I've had two machines (one was an Intel D945GCLF and the other was a core2 duo board that I can't recall the model number) that will see the flash drive in the BIOS but when told to explicitly boot off the drive it simply boots into the OS on the hard drive.  I am using HPUSB for the formatting tool and GrubInstall for the MBR Tool.  I still had a flash drive that I had created with a 2011 version of WinBuilder and that one worked on both machines.  Any ideas?  On a side note,  I tested this method (first post) of using ntdetect, ntldr, boot.ini which calls grldr and it booted on one of the problem machines (the other machine I no longer had access to).  Any ideas why this would work?

In Win7(8)pese, the scripts Copy to USB although "fairly complete" are basic scripts which is sufficient in most cases.
HPUSB is kept for historical reasons but I believe that it is allready better to use BootICe in these scripts.

No ideas why this method would work, there are more qualified than me to answer.
But look at other tools also for more flexibility, multi partitions...