I saw this when returning to my profile page via the browser's back button:
Fatal error: Base lambda function for closure not found in /var/www/sites/huddler/releases/bfba393107cd74cd8c4637c16305b69e54948925/v2/system/application/modules/users/views/following/following_widget.php on line 3
The URL was http://epicski.onthesnow.com/u/29912/Xela
When I did a reload, the problem was gone.
I'm using Safari 5.1.9 on Mac OS 10.6.8, but this doesn't seem to be a client-side issue.