Since June 2008, I have had a Windows 2000 system connected to a Vista
system thru a router.

I have several shares defined on the Windows 2000 system.
No shares are defined on the Vista system.

On 28 April 2009, I replaced NIS 2008 with KIS 2008 on the Vista system.

On 23 June 2009, I noticed that the Vista system could no longer COPY files
from the Windows 2000 system to the Vista system, tho Vista could still open
the files.

I know that, on 19/20 June 2009, the Vista system copied files from the
Windows 2000 system. So something broke after that.

As I recall, there was a Windows update installed on 23 June 2009. Perhaps,
that update changed some settings?

What do I need to look for?

Is this a known problem?