Error - compilation failed/header information when creating page - multisite

Hello, I am installing WP multisite using subdomains. Twice, iv'e an error when creating/editing the first pages - compilation failed, quantifier does not follow a repeatable item at offset 1 in.'classwp.php'.. and header information, headers already sent by 'admin' header.php - The option to change homepage disappears and I have had to restore site(twice). SG advised this is a theme error. The only non standard part of my installation is adding sg https enforce code to htaccess. I have not had any problems until multisite/brilliant theme.