Error message

• Warning: Cannot modify header information - headers already sent by (output started at /home/pearltri/public_html/includes/common.inc:2820) in drupal_send_headers() (line 1501 of /home/pearltri/public_html/includes/bootstrap.inc).
• Error: Class 'CToolsCssCache' not found in _cache_get_object() (line 32 of /home/pearltri/public_html/includes/cache.inc).