[c-nsp] Unrecognized midplane in chassis 7200

[Brian Turnbow]

Hello all, 
I have an issue on a 7200(non vxr) with an npe 300 that's driving me
nuts.
The router was running 12.0.22S and all was fine. An upgrade was
attempted into 12.3.x  , for x we  tried  17 18 19 20 ecc.. 

At boot with any 12.3.x train I get a message 

%%Error: Unrecognized midplane in chassis
 
If I boot the 12.0.22S , life is good. I tried 12.0.32S and that will
boot as well.
Is it possible that the eprom does not support 12.3.X ?

On the web I cannot find anything related to this error message, besides
a bug on the npe-g1.

Here is the actual midlane  eprom version info 

C7200 Midplane EEPROM:
        Hardware revision 1.3           Board revision M0
        Serial number     18283396      Part number    73-1539-03
        Test history      0x0           RMA number     00-00-00
        MAC=0001.97de.7800, MAC Size=1024
        EEPROM format version 1, Model=0x6
        EEPROM contents (hex):
          0x20: 01 06 01 03 01 16 FB 84 49 06 03 03 00 01 97 DE
          0x30: 78 00 04 00 00 00 00 00 00 01 8A B0 FF FF 00 FF


Thanks 
Brian