Using Versioning Manager, add a new CVS profile of type ext.  Enter the
parameters for working directory, cvs server, repository path, user, etc.,
progressing down the fields in the dialog in order.  Then when you reach the
external client, point to a valid external cvs client.  An error appears saying
this is an invalid client, and the Versioning Manager disables the Finish button
so it is impossible to save the settings or the create the profile.  I tried
with both C:\Program Files\CVS\cvs.exe and C:\cygwin\cvs.exe, both of which are
valid cvs clients (the one in Program Files is the latest stable release from
cvshome).  I eventually created a profile by deleting the Hidden settings for
vcs in the user dir (along with var/cache), and trying every permutation of
field entry orders.  This took hours to find!  One of them eventually worked,
which I can't even reproduce for anybody else.  Even then I could get it to
accept the cygwin client, but not the cvshome client.  After creating the
profile with the cygwin client, I could immediately Edit the profile and change
it to the cvshome client, which works perfectly fine in Netbeans for all cvs
operations!

So, there is a bug in the validation of the external cvs client field in the Add
dialog of Versioning Manager that prohibits creation of cvs connections, render
the vcs completely unusable.

Also, there are Versioning settings that are not in var/cache and not in the
Hidden vcs settings of userdir.  It somehow remembers old settings, which kept
getting in my way.  Where else does it store settings and how can I delete them
when they are messed up.  Specifically, I cannot delete the settings that appear
when I pick a Working Directory that it has seen before.  It then autofills old
settings.

As a suggestion, since Netbeans caching errors are a frequent source of problems
for users, it would be great if ALL such settings were in var/cache so that we
could easily delete them when they are messed.