My server has some shared folders for client access, but after every logoff/ shutdown of client PC, on connection server asks for a username & password prompt,
How do I auto pass the credentials using batch file or sume another method.
Please guide.

It is probably doing this because of saved credentials. The saved credentials are not correct so you are being prompted. To view or edit saved credentials, click Start, Run and type the following:

%windir%\System32\rundll32.exe keymgr.dll, KRShowKeyMgr

Click OK. You should get the window that shows the previously saved credentials.

...
It is a question

It is probably doing this because of saved credentials. The saved credentials are not correct so you are being prompted. To view or edit saved credentials, click Start, Run and type the following:

%windir%\System32\rundll32.exe keymgr.dll, KRShowKeyMgr

Click OK. You should get the window that shows the previously saved credentials.

You mentioned that you have a SERVER so I assumed you were using a domain security model. It is possible that you are using a WORKGROUP instead, so I will add that when using workgroup security, you should add the accounts from each machine into the security for the machine you are trying to connect to. For example:

If you have three computers named ONE, TWO and THREE and you have a shared folder on computer ONE named SHARE, then check the following:

On computer ONE, go into the Users and Groups and open the group which has appropriate security for the shared folder named SHARE and add the groups from computer TWO and THREE which need access. If each machine has a group named Users and the accounts on each machine are members of the group Users then add the accounts for TWO/Users and THREE/Users to the membership of ONE/Users. The members of each of these groups will inherit the permissions of the group.

Also, check the Share permissions for the shared folder on computer ONE. Make sure that the ONE/Users, TWO/Users and THREE/Users groups have at least READ permissions for reading files and WRITE/DELETE (Change level) permissions for being able to make changes.

When the groups are members of the appropriate group on the shared machine, you will not have to constantly supply permisssions every time you wish to make the connection.