The error message can look similar to this message:
% Invalid IDPROM image for linecard in slot 4 (error = 3)
This error indicates that the linecards installed did not boot correctly because the supervisor generated a bad signal onto control bus.
In some scenarios, it is seen that improper seating can also cause the ilinecards not to be recognized on Cat6500 chassis.
This problem is also documented in Cisco bug ID CSCdz65855.
If you still see that the error reoccurs, then open a service request with the TAC Service Request Tool.