AMD Processor Model Unknown for Nvidia Geforce 8200

Hey guys..PLLLLLLLZZZZZZZZ HELP...it's a real problem 2 me!!

I've the XFX NVIDIA GeForce 8200 Motherboard (AM2/AM2+) ..and i was using as a processor : AMD Athlon X2 4200+, now I've Upgrade my processor to AMD Phenom II x4 940 BE running on 3.00 GHZ ..but i've just shocked that the bios reads it as "AMD Processor model unknown" but it recognise that it's speed is 3.00 GHz..also on starting windows (I use windows 7 RC) it tolds me the same phrase..what can i do to make my PC recognise the processor...I REALLY NEEED HELP GUYZ..