- I keep getting this error message I have set up url

Hi - I keep getting this error message
I have set up url groups but no regular expressions. and that option is set to no. This error has only appeared since I added the url groups so am presuming it has something to do with that but maybe not.

"Warning: preg_match(): Compilation failed: regular expression is too large at offset 38726 in /home/progress/public_html/wp-content/plugins/membership/membershipincludes/includes/functions.php on line 1103

Warning: Cannot modify header information - headers already sent by (output started at /home/progress/public_html/wp-content/plugins/membership/membershipincludes/includes/functions.php:1103) in /home/progress/public_html/wp-includes/pluggable.php on line 875"

Any help would be greatly appreciated.

Linda