Thanks nekrosoft13 from our BPN Forum
SYMPTOMS
When you try to open a file through a network share by using the SMB protocol, the file may take a long time to open.
CAUSE
This problem can occur when a Windows XP client also has the file open and owns the oplock to the file. It does not respond to the oplock break request, and because of this, the server waits until the request times out and the other client has to wait for that.
RESOLUTION
A supported fix is now available from Microsoft, but it is only intended to correct the problem described in this article and should be applied only to systems experiencing this specific problem.