iscsi boot

[bman68]

I have a 5406zl and a thin client connected to it. It is PXE booting a Win7 image via PXE then TFTP. Windows 7 starts to boot (see spinning circles) then hangs. If I plug the client into the server directly or into a Linksys mini switch (hub?) it works flawlessly. Both Cisco and HP switches fail me. I configured portfast (cisco) and mstp (hp) but still nothing. What could be blocking the bootprocess ont he switching side during the Win7 boot? Port transition is what I thought it was but not sure