Help! Getting error message after multisite install

Hi all,

I have successfully converted one of my blogs into a multisite installation. I have also added and successfully carried out domain mapping for a second site. All was working just fine when for no apparent reason that I can figure out, I started to get the following error message:

Fatal error: Call to undefined function is_rtl() in /home/jnielsen/public_html/wp-includes/general-template.php on line 2102

I have been unable to trace down any of the function files that contain the function the message says is missing.

I can view both the blogs, so this just seems to effect the dashboards for the blogs.

Any help would be appreciated.

Jerry Nielsen