Mike,
For a vserver in a transparent caching setup, you would configure no nat client, no nat server, but for most other traffic, you will want nat server, no nat client.
If you are refeffing to "ip nat" under the interface in the MSFC config, remove that from the CSM vlans.
For bridged mode CSM, the real server gateway is the MSFC vlan address on the CSM client vlan of the CSM, not to the CSM VIP.
If you config nat client, you also must config a nat pool for the CSM. In this case, the client source IP is replaced with a nat pool address.
Peter