I have had a similar problem, but only when a user is in a Joomla access group that isn't properly configured. I'd check your Joomla groups and access levels.
oxiepagen wrote: Hello,
I have gone from 1.5 to 2.5 and migrated. After having updated CB 1.9.1, I get a white page when going in to a user page. How do I solve this?