preg_match error relating to inability to convert object to string

I was receiving the following errors when applying an action:

Object of class stdClass could not be converted to string in /var/www/reaa/includes/bootstrap.inc on line 785.

preg_match() expects parameter 2 to be string, object given in /var/www/reaa/includes/bootstrap.inc on line 788.

It was tracked down to drupal_validate_utf8 in check_plain(), views_bulk_operations.module line 892

The attached patch ensures the check_plain'd parameter is indeed a string, and not an object

DT

P.S Thanks for the great module! it's very useful :)