Karl,
It is well-known that various VPN software causes problems with
Cygwin/XFree86. The reasons for this are numerous, but it primarily has
to do with the fact that these VPN packages replace various Windows
system DLLs with their own versions that do not correctly duplicate all
of the functionality of the Windows networking DLLs. There isn't
anything we can do to fix this problem, as we certainly cannot write
code to deal with x number of networking layers for Windows.
The only real solution here is to never install the VPN software to
begin with, as most of them leave their modified DLLs in place when you
uninstall them.
You misunderstood:
I didn't get the "no buffer space available" error with the VPN in place.
I only had very slow performance.
The error happened at work, no VPN, both machines inside the firewall.
The problem would have nothing to do with the window manager.
I consider your problem solved, as there is nothing I can do to help.
You could ask the Cygwin list (cygwin@cygwin.com) if you have further
questions, but I would expect it to get toasty in there if you aren't
offering to help :)
What kind of help did you have in mind?
Karl