backflashing problem from Asus Rampage Formula back to original P5E deluxe (X48)

Hello, i have a severe problem: i would like to backflash from the 0902 Rampage Forumla Bios to my original P5e deluxe lates bios 0501 (i have crossflashed this 0902 rampage formula bios several months ago with afudos229es.exe /pbnc /n) but now i cannot go back agaian:
every software afudos220es, afudos229es, afudos236es, and also asus update v61002 and v61001 (under win xp) and lates v717 (under winVista64 or Win7 64bit) and also the BIOS build in Asus EZ Flash 2 do not want to flash back with the following "ERROR: Rom file boot block is not valid". any ideas?

within DOS: when i do not use /pbnc /n switch i get an different error: ROM file ROMID is not compatible with existing BIOS ROMID.
and when i use like explained in the threads here across the board (afudos /i<biosfile.rom> /pbnc /n) i get ERROR: Rom file boot block is not valid.

has anyone an idea what happened to my rom file boot block? i applied once the SLI modded hack with the slistringinstallerv2.exe from xdevs.com, but this did just patch in windows on hdd and not my bios i think, and i also uninstalled everything again, and even deleted hdd ans so on...
my ROM boot block cannot be invalid, because the board works and boots like a charm with rampage formula bios, but now i just would like to revert it to its original state, and its a no go :confused: :(

so do i need a special p5e bios to get back from the 0902 rampage formula one? or do i need another afudos tool? with different switches?
(i usually