XP Client connection to Win2000 Server Problem (update)

Hi,

We have some WinXP Pro joined to the domain of an NT 4.0 Server. This NT
server was trusted with a Win2000 Server. When our XP connect to this
Win2000 shared path and open a text file. At the beginning, it is Ok to
open, edit and even save the file.

However after some time, it will automatically prompt with the access
permission error: "\\Win2000ServerName\SharedPath\ is not accessible. You
might not have permission to use this network resource. An operation was
attempted on a nonexistent network connection."

If I try to save the text file at the moment, it will prompt with the error
of unable to save : "Connot create the
\\Win2000ServerName\SharedPath\TextFile.txt file. Make sure that the path
and filename are correct."

We also have some client application running on the WinXP connecting to the
Win2000 DB engine, which is also affected by this connection problem.

This is the things that I have done and tried :
- When the problem happens again, I am still be able to ping the Win2000
server from the XP(also can access the shared path)
- The shared path and the sub-folder of the Win2000 has been granted with
"Everyone"
- In the XP network properties, I go to the device and disabled the "Allow
power off to turn off this device"
- I have try to increase the licence in Per Server in the Win2000 Server.
But seems all cannot resolve this.

Thanks,
Kent