I've recently installed an Apache (v2) server on my windows box, along with PHP5, MySQL v4.1.16 and everything else needed to run XOOPS (prior to this and even now my site is being hosted, I am just attempting to host it myself).

Anyway, here's the problem, every time a new user tries to resgister he goes through the usual registration process of filling out his info, then submitting it, but once he gets to the "confirmation" screen with the "Finish" button on the bottom which he then hits and is presented with a 500 internal server error window.

The funny thing is that everything else works, even when I am as the administrator registers that new user through the administration control panel, new values get written to the db and everything works perfect except when a user himself goes through the abovemention.

If anyone has any ideas please share.

I have the same problem, apache2, linux, php4 though, and the server logs suggest there is some problem with the email, it says malformed header.
I am still looking into it, but if anyone has any suggestions... this would be the place
Neil.

ok, after some sleuthing, I find that .. if I turn off "notify by email when new users are registered" in Prefs/User info settings, then register.php does not croak. and users get past the second screen of registration process.

My site has multiple webmaster users, (2), and the first one get the email, but the second one doesnt, it's a malformed header that causes the 500 error.
So possibly a bug?? At least now that I have isolated the problem, and have a workaround (TURN OFF email notification of new users), I can spend a little time trying to sort this out.
But, if anyone of the devs out there want to try this:
Manually create 2 or more admins.
Turn on email notification of new users,
logout.
then register as a dummy user. Does page two, upon posting, croak and die - with an internal server error?

xoops 2.0.15 linux/apache2/php4