Problem after updating asus bios

using asus EZ flash 2 utility i updated my bios from version 0608 to new version 0901from asus update site on post i get a msg; 'Unknown CPU detected,bios update is required to unleash its full power'.
i now have to hit F1 to start up, i tried to downgrade back to version 0608 but i got a msg; 'Downgraded rom file was not suitable for the system'
however it did let me downgrade to version 0803 which is were im at now, so how can i get back to version 0608 or is it possible to fix the unknown CPU msg.its the first time ive tried to update bios and probably the last.i would be very grateful if any one could help me to fix this.

yours hopefully
robbie