[TxMt] Blogging Bundle Login Broken

[Mark]

This is some weird behavior. I've installed the Blogging bundle. Put in 
my blog details like this:

     blog_name  http://admin@my_blog_url/xmlrpc.php

I successfully fetched posts. Once. Then it started failing with this 
message:

     Error: Bad login/pass combination. (403)

I deactivated all my Wordpress plugins. Same error. I went into 
Keychain, deleted the password; tried fetching posts again (pasting the 
PW into the dialogue box), and it works -- until...

I try fetching my blog's Categories, and get the following error:

     Received exception: XMLRPC:: FaultException
     XMLRPC:: FaultException: Bad login/pass combination.
     [Several more lines of information, but I don't know how to capture 
it!]

...And from that moment on, trying to Fetch Posts -- pasting the PW into 
the dialogue box because the PW is no longer in the Keychain -- fails 
with the "Bad login/pass" error. Can anyone help me figure out what on 
earth is going on?

TIA,
Mark

Using:
     TM 1.5.10 (1631)
     Blogging & Multimarkdown bundles
     OS X 10.6.8
     WordPress 3.4.1