said by rlxo :ip nat inside source list 1 interface FastEthernet0/1 overload
ip nat inside source list 2 interface FastEthernet0/0 overload
Where's your ACL 2? Also take a look at how your NAT's constructed; namely if ACL 2 specifies something
entirely different than from ACL 1, how is it supposed to fail over?
Don't know if you have any capability of running a routing protocol or something else with the upstream
router. You could also look into OER / IP SLA rather than running two static routes, just as a thought.
My 00000010bits
Regards