updated Membership Premium... broke site

i had installed Facebook Ultimate and the system was generating error
an error saying "check your facebook privacy settings, you may have previously blocked this app" .... when i updated membership the facebook login started working but now every page except "Register" and "Account" return the message
"Fatal error: call to undefined function mb_strips() in blah blah lah membershipincludesincludesfunctions/php on line 1082"

please help