A client have a apllication with many exe (CLIPPER) and files (dbf)

On a server nw 5 many users work at the same time.

On a server nw 6.5 sp7 only the first work. the second user when launch the apllication wait until the first exit. On the server the message is

comn - 3.26-592 nnid=F000A

station xx timed out waiting for an op-lock on file xxxxxxxx.dbf
held by station xx

Please help me