Ways to fix it:
- use stock recovery
- noogie on an SD card, restore backup
- noogie on an SD card, try putting an override in default.prop in uRamdisk
- noogie on an SD card, use a Linux host to edit /system/build.prop
- noogie on an SD card, make a backup, hexedit b.p, restore
- noogie on an SD card, install Clockwork Mod Recovery, then use ADB to fix b.p
- use omaplink.exe to boot Clockwork Mod Recovery over USB, then use ADB to fix b.p
Well, that's about all the ideas I have.