We have a problem using an NM-16ESW in a 2811 routeur. Actually this network module works perfectly in routing mode (no switchport on the interfaces) but we are not able to use it in switching mode; Our configuration is very simple: We have configured vlan 100 in vlan database, we have configured interface vlan 100 and set an ip address to this interface vlan 100, then we have put the interface Fa1/0 (first int of the NM-16ESW) in vlan 100 (switchport mode acces, switchport access vlan 100). But there is nothing to do and we are still unable to ping (of course we've checked that interfaces are up)!!! Thanks for your help because this problem is going to drive us crazy !
It looks like you have a 4port HWIC also in the router. You may want to remove it and retest. I remember trying to use a 9 port HWIC with a 36 port ESW in a 2851 and they could not communicate with each other. However now I just have the 36port ESW in several 2851's and they work fine with basically what you have configured.