Comment 1 for bug 357799

I had a similar problem using 9.04 64bits server edition.

AuthBasicAuthoritative Off was present, so authentication was really made with MySQL data.

I could enter login and password, but then I got a blank page and /var/log/apache2/error.log reported child pid <xxxx> exit signal Segmentation fault (11)

I found interesting info on ubuntu lists: https://lists.ubuntu.com/archives/ubuntu-users/2009-January/172447.html

After switching back to 9.04 32bits, problem was solved (I used the same configuration file in both cases)

It seems that there is still a problem with libapache2-mod-auth-mysql 4.3.9-11, which prevents me from using the 64bits edition