hi, i am new to drupal and i am trying to create an image gallery, upon downloading and installing it i realised all of my pages have the the full page and then half of it again underneat it and then the following message on them

" •Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\includes\common.inc:2561) in drupal_send_headers() (line 1040 of C:\xampp\htdocs\includes\bootstrap.inc).
•EntityFieldQueryException: Field storage engine not found. in EntityFieldQuery->queryCallback() (line 1048 of C:\xampp\htdocs\includes\entity.inc).
"

Does anyone have any ideas what it could be ?