You've confirmed that the mmaccesskey.ini file is valid within the pxemanager.ini file and you've used the pxekeymatch.exe utility to confirm everything is in sync. You've even use the dskeygen.exe utility to build a new mmaccesskey.ini and you still can't get into the PXE Configuration Utility.
Development is currently looking into this.
Applies To
DS 6.9 sp1 and sp2