Hi Syed,
Really need more of a context to your problem.
1. You've posted in the SSO forum. A SSO problem or a normal SAPGUI logon problem ?
2. You say .... "And the standard RFC which i'm using for authenticating user is SUSR_LOGIN_CHECK_RFC" .... Meaning what ??? you are using a home developed solution ?
3. Problem affects one user or all users ?
4. Backend version and kernel pl level please.
Cheers,
Amerjit