Headers already sent by s2member

Hi there,

I’m having a serious ‘headers already sent’ issue with s2member. I uncovered this issue because the site redirected to wp-admin instead of the Welcome page (even though I set it correctly) (same problem here).

I enabled WP_DEBUG and there seems something very wrong with line 97 in cache.inc.php :

WARNING: wp-includes/functions.php:1719 - Cannot modify header information - headers already sent by (output started at /home/salvi/domains/site.be/public_html/wp/wp-content/plugins/s2member/includes/classes/cache.inc.php:97)

WARNING: wp-includes/functions.php:4662 - Cannot modify header information - headers already sent by (output started at /home/salvi/domains/site.be/public_html/wp/wp-content/plugins/s2member/includes/classes/cache.inc.php:97)

WARNING: wp-admin/admin-header.php:9 - Cannot modify header information - headers already sent by (output started at /home/salvi/domains/site.be/public_html/wp/wp-content/plugins/s2member/includes/classes/cache.inc.php:97)

NOTICE: wp-content/plugins/s2member/includes/classes/admin-notices.inc.php:136 - Undefined index: page
NOTICE: wp-includes/capabilities.php:1060 - Trying to get property of non-object
NOTICE: wp-includes/capabilities.php:1061 - Trying to get property of non-object
NOTICE: wp-includes/capabilities.php:1064 - Trying to get property of non-object

A picture from Debug Bar:

When browsing around I see that this “devilish” line 97 is causing more problems. I’m using s2member in combination with W3 Total Cache. I now disabled W3 Total Cache and the bottom three notices disappeared.

Do you have any idea what might be causing this?