WinME won’t connect to a Win2K Server?

I have a Win2kPro PC, 2 WinME PCs, and a Win2K Advancd Server. Both Win2K (Server and Pro) talk to each other just fine, and Both WinME Boxes log into the Domain on the Win2K Server. They can both write and read small files to the Server, but, ifI try to move a large file say over 50MB the ME PCs loose their network connections and can’t see anything on the network. I know that ME dosen’t have a problem connecting to a NT domain so why the issue with a Win2K domain?