Hmm. I just tried this from a DQ45CB and Win7 is installing now. Maybe I havn't waited long enough yet; at what point during the install do you see the failure? Or could it be specific to a DQ57TM? Also, I used RIL instead of commander: http://communities.intel.com/docs/DOC-5943. Maybe that'll help?
Anyhow, I'll let my install finish and see what happens. Let me know if you find anything or have more details about the failure.
BTW - You can make the remote install faster by:
Extract Win7 ISO files to a shared drive
Build a WinPE ISO http://communities.intel.com/docs/DOC-5095
Use the linked UCRD to boot WinPE over IDEr http://communities.intel.com/docs/DOC-5552 (this step is optional).
In WinPE, map the share and run setup
This way, most of the install files arew copied with in band network drivers (via WinPE) which are generally faster than using IDE Redirection.
This sounds like a BIOS problem I encountered once where the BIOS replaced the 1st boot device when it received IDEr request from remote instead of simply adding another boot device to the top of the bootable devices list.