samba - Sep 2012 - Strange Windows 7 > Samba problem with unrelated CIFS mount by Samba server down

Hi,

This problem is solved in our instance, but want to report it here because
I'm curious about the root cause, and also for others who may see it.

We have a Samba server (3.4.7) which is mounted by various Windows
workstations. It also, unrelated to that, has CIFS mounts of a half-dozen
other Windows servers. Today we turned off one of those half-dozen, without
removing the autofs mount of it on the Samba server. At that point we
discovered that user workstations using Windows 7 (but not Windows XP or
Linux) were having serious trouble copying files from the Samba shares on
the server. 

Turning the CIFS mounted Windows server back on resolved the problem, as of
course did removing it from the list of autofs mounts and then turning it
off again.

But what is this dependency about? What is a Windows 7 client doing in
negotiations with a Samba server that would allow it to list files just
fine, and begin to transfer files, but have that transfer stall and fail
more often than not, just if an unrelated CIFS mount by the server of
another Windows system happens to be down? I know there were lots of
"security" additions in Windows 7. But I can't figure out how
"We'll copy
files, but undependably, in this circumstance" qualifies as real protection
from anything. Just seems weird.

Anyone know why the one thing should depend on the other here?

Thanks,
Whit