I can go through the whole process of adding a chat account without a problem (Edit -> Account Settings -> Account Actions -> Add Chat Account... &c., &c.); however, when I click "Finish" at the end of the process, nothing happens whatsoever.
The Finish button remains focused, but doesn't stay in "clicked" state as might indicate that something is going on in the background; the account does not appear in the list under "Account Settings", and I can't see (via netstat) any newly opened connections, or even (via top) any increase in CPU activity for the thunderbird process, all of which would seem to suggest that, well, nothing is happening when I click "Finish".
The options chosen in the Chat Account Wizard (account type, username/password, server settings for XMPP account, &c.) have no effect on the problem; whatever I specify, "Finish" continues to do nothing.
This is Thunderbird 17.0.4 ESR x86_64 binary build, the tarball of which I downloaded from Mozilla and unpacked as per directions. The platform is RHEL5, which unfortunately isn't up to me; neither do I have root on the box.
Everything else in Tbird works, including Exchange integration via DavMail Gateway; only chat poses a problem. I haven't been able to find anything via Google, or in Bugzilla, to explain what's going on.