Can view 'media' tab in WordPress - receive 'Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0'.

I've just installed SSL cert on a WordPress site and had to modify some files + install a few plugins to get rid of those nasty 'insecure content' errors when hitting the site via SSL. Anyway, when clicking on the 'media' tab within the WordPress admin menu I received 'Fatal error: Unknown: Cannot use output buffering in output buffering display handlers in Unknown on line 0'. The culprit was 'WordPress HTTPS' plugin. Disabled that puppy and it was all good. I also noticed that the 'WordPress HTTPS' plugin seems to slow the site down a little bit, so use with caution!