WinPE network drops?

[Bryan_Lucas]

WinPE boots successfully via CD and/or PXE on any number of ProLiant models that we deploy. Everytime I run winnt32.exe for my unattended build, the Windows build will stop at some point and leave me in the WinPE shell. (And my network share is unreadable)
Then networking returns...kicking of winnt32 again, may or may not work the next time, but does eventually work.

Notes: using WinPE 2005 that includes the ProLiant drivers including RIS/WinPE broadcom driver released 3/21/2007. DHCP and physical network has been ruled out. (everything is set to 100/full and portfast enabled as well)

Any ideas?
Thanks.
-Bryan