Default [Q] a57 ninja 3 problem stuck in nninja logo

i'm using micromax a57 when i try to install the stock rom i get this below messages please do help me
-Installing: /sdcard/LQAEB26_2012-12-20_factory_update.zip
Finding update package...
Opening update package...
Verifying update package...
Installing update...
assert failed: package_extract_file("nv.cfg", "/sdcard/image/nv.cfg")
E:Error in /sdcard/LQAEB26_2012-12-20_factory_update.zip
(Status 7)
Installation aborted.




please help