Error 500 when updating profile

[Ribberholt]

Hello
Recently I have encountered a problem using userXTD profile. When my users try to update their profile on frontend, an error 500: default layout not found. I ran Joomla in error checking mode, and it seems to be the windwalker framework, which I assume is a part of the userXTD extension, as I use T3 for the rest of the site.

What should I do?
FYI I'm a newbie at joomla, and English is not my native language. So please be precise.