Error Description: InfoPath Forms Services has detected a mismatch between the user's data in the browser and on the server. This may indicate the SESSION_STATE_PASCAL_CASED is not configured properly on a multiple front end farm or that a malicious user is trying to tamper with client data.
Possible Fix: Clear browser's cache and try again and if that doesn't solve the problem then run the following command:
stsadm -o reconvertallformtemplates
-SSA
ssa