I have searched a lot about the problem. On Google and this site. However, one can get run in circles looking for answers on both. Gets frustrating.
As I posted, it works on wordpress.com, which I understand to be WPMU, but not on other installations. There is the stylesheet issue with wordpress.com, though. Just putting in the URL on wordpress.com when adding to Live Writer was enough to get it to work. I have tried all other combos on Live Writer with my own installation with no luck. Some of those come back with that same wp.getusersblog error.
Using Live Writer with WMPU is a major enhancement, and it is surprising that there is so little info on it.
If you Google about WMPU you will find issues regarding support in the community that leaves a lot to be desired. Such leads to frustration on the part of those giving it a try. Some of us do it as a hobby and not as a commercial enterprise.
Mr. Billets, I apologize for railing on you, as my post that was unanswered on the subject for over 3 days previous to that post kind of set me off. You have been gracious in YOUR response to my frustration.
Unfortunately, the storing of info on forums such as this one and most others makes it very difficult to follow threads. You have the posting in the wrong place, the different releases, the going off on tangents, and all sorts of things to frustrate people looking for answers. The nature of the beast. In the absence of a nice updated FAQ where some of those issues can be readily resolved a little kindness and understanding on legitimate inquiries goes a long ways.