I've been working on the same issue with 4500s and 3640s. The response I got from Cisco was to try one of 2 things. The first of course is their initial response to everything -- reboot.
The other was to remove the snmp-server config, write to memory and then readd the snmp config. This didn't work for me but it might for you.
My TAC case is still open but I'll return to this posting if we do come up with a solution.
Good luck!
TAC Case -- CSCea67346
When you add a GSR device to RME, it may appear in the Not Responding state.
This happens only if the processor RAM of the device is greater than or equal to 2 GB.
Workaround:
None.