Server received an incorrectly formatted

I have the following setup.

Nt Server 4.0 Build 5 the clients are Windows 98, Windows 95 and Windows 98 SE

I keep getting this error message in event viewer.
The server received an incorrectly formatted request from \\edi

I have switchedout NIC cards and replaced cables. It doesn’t help. The users are not complaining. I just notice the messages when I check Event Viewer.