Members directory Plugin and categories Conflict

Hello, I'm having a strange problem with "membership directory plugin".

Using wpmu/wp 3.1 with Triden theme all updated to current.

Categories get "broken". I have permalinks set to "Month and name" and category base is "articles". when I activate the member plugin, the category archive pages become 404.

If I reset permalinks to "default" then categories come back, but then I get these errors:

members directory page - Members » Invalid User
Member not found.

and blog directory page - "Invalid page"

I tried this on another thread last week, but only got one response which was to switch the theme. But, that didn't work. any other ideas would be greatly appreciated. Thank you!!!