I had already a few issues regarding to thunderbird at my office. But today two bugs met each other and decided to show me live in hell :P. If you have user credentials stored in an LDAP directory and using nss_ldap for the naming resolution you'll have to start the glibc nscd or thunderbird will segfault at startup. That's not the problem I thought and enabled nscd per default. This workaround for this combined glibc/thunderbird bug worked well until now.

With glibc-2.6.1 installed the nsswitch stops working properly if you enable nscd! I do not have investigated the real problem and I am not willing to fix this crap but I can say that the NSS is not behaving the way I'd expect. If you have

 passwd:      files ldap
 group:       files ldap
 shadow:      files ldap

set in your nsswitch.conf a call to getent passwd would show you all your LDAP users (if everything is configured the right way of course) but an id $USER won't bring you the uid and all the other stuff - it simply says: id: $USER: No such user. No more information - nothing to debug. You're not able to login as LDAP user anymore. You could disable nscd -> but than you can't use thunderbird with LDAP enabled :(.

A strace id $USER pointed me to nscd and I'll solve the issue with disabling LDAP in thunderbird. That's not a solution - that's even a bad workaround - but that's all I can do ATM.