Sanjay, I'm no VB expert, just a DBA that has had to deal with VB developers. Usually, I say that if SQL*Plus works correctly, then SQL*Net is correctly configured so the problem must be in VB or the Microsoft configuration. All the things you mention that you tried simply confirm that SQL*Net is correctly configured. You say that one of the PC's works correctly. I would try to find out what is different about the VB configuration on that PC vs. the other two. I think that will likely correct the problem. Unfortunately, I can't tell you what to check on the Microsoft side. Are you using ODBC? Dennis Williams