Strange warning messages above my blog header

There is a strange series of Warning messages that have recently appeared above the header of my blog at https://www.goodpoliticsradio.com

There are 6 of the following messages: Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 1 in /home/goodpoli/public_html/wp-includes/classes.php on line 95

The messages reference lines 95 and 96 of the classes.php page in wp-includes. I looked at the lines and they look OK to me. Does anyone know what these warning messages mean and how to clear them?

Thanks
Leaddog