Record locked by another user - BDE 4.51

we have an application with DBase Tables running under
a) Windows NT Server and Clients
b) Novell Netware with Novell Clients.
with BDE 4.51.
When starting our application, we sometimes get the error ' Record locked by
another user'.
We cannot reproduce this error on some other Windows NT machine or Windows
98/95 machine.
What may be the reason for that ?
Thanks in advance for any help and kind regards