Nitesh,
The User buffer loads are based on the USTxx tables and not the real USRxx tables. The USTxx tables get out of sync over time and the "automatic" reset will not correct the problem. In those cases PFUD, SUPC and PFCG user reconcile and profile gen cause the reset.
PFUD (RHAUTUPD_NEW) a client dependent program that makes select statements to the table UST04 and tries to refresh it. So while doing this activity, it would have deleted the other roles which doesn't have profiles and already deleted from the system.
Let me know if you need further information or you can close this thread.
Regards,
Deepak M