Your description is still not clear.
I take that you have clients running in Windows 7, and the communication to SQL Server work for these clients. Does this communication still work, when you connect the Windows 10 machines? Or are they stalled?
I hope that you are aware of that SQL 2000 is seriously out of date, and connecting something Windows 10 to SQL 2000 may not work, although it depends on what client API you are using. If you can give details on the application, we may be able to help you.
Else, the only advice we can give is: Upgrade, it's long overdue.