Squirrelmail pouts! (page not found after sending)

[vputz]

I have this issue on my gentoo box and I'm having it now on a debian-based NSLU2, but it's the same problem. Sometimes--and not all the time--when I try to send a message in SquirrelMail I get a "page not found" error; using the back button gets me to my "type your email" page again, but of course everything is lost. I've now gotten into the habit of copying everything to the clipboard, sending, page not there, back, repasting, sending, page not there, back, repasting, sending, oh hurrah, it worked!

This is silly. Anyone know what's up? Gentoo box was using courier-mta/courier-imap, then postfix/dovecot; NSLU2 is using postfix/dovecot. Same error on all of them.

Any ideas?