I don't believe so, InfiniteSilence. This is a WebLogic server, I don't know if .htaccess is even a factor.

One difference between our tests is that my (under test) form does a POST to a separate validator that either redirects to the appropriate page, or returns a 403 if you give it invalid info.

Say, thanks, that may be the critical difference. I've been re-re-reading the docs on WWW::Mechanize and LWP::UserAgent, and I think the next logical step would be a rewrite of my simple case to use LWP::UserAgent directly.

(I'm leaving out the additional troubleshooting that's led me to that conclusion, I think it would only muddy the waters. Suffice to say I believe I can build a test case at home over the weekend that mimics the problem, and then see whether LWP::UA solves it.)

--pilgrim