Problem in SLDCHECK

Hi All

I am facing a problem in SLDCHECK While i am executing sldcheck .sometimes Function module Exchange_Profile_Get_Parameter is returning code 3 and asking for SLD logon details.i am facing this problem only on few occasions not all the time .My LCRSAPRFC is working fine and is pointing to correct hostname.

please provide me with a solution

Thanks and Regards

Uday