[syslinux] inconsistent Int 22h local boot

[Miguel]

I have a Dell 1435 system that will not respond correctly to a com32 call
to Local boot

 Int 22h
 AX=14h
 DX = 0

This call should not return. It should unload the PXE+UNDI stacks and
continue the boot process with the next boot device.

This call is working fine for me on an HP DL360G2 and on a Dell PE 850.

But, on this Dell 1435 the call is returning from the Int 22h.

I am using syslinux 3.51

Q: Any suggestions?

Q: Is there any info/data that I can collect that will help identify what
is causing this problem?

Thanks in advance,
Miguel