Random and Frequent 500 Internal Server Errors

Memory issues can be from anything. JFBConnect's footprint is very small. However, if you were just under your limit before adding it, it's definitely possible that JFBConnect has pushed you past your limit. It doesn't necessarily mean JFBConnect takes a lot, it's just that it's the proverbial straw that broke the camel's back.

Beyond that, the only thing we know of that's causing some errors right now is the Kunena profile plugin. If you have that enabled and are using Kunena 2.x (released at the end of June), you should disable it.

If that's not the case, I'd highly recommend turning on Debug Mode in Joomla's Global Config. It will tell you roughly how much memory each page load requires. You may be able to get an idea if a certain component view is pushing you really close to the 24M limit.

Also, 24M should be enough, but if you're running any 'big' extensions like CB, JomSocial, jReviews or countless others, that could easily be too small. This site's memory requirements per page are always under 20M. However, we have PHP configured to allow up to 64M if necessary.. sometimes a cron job or other background task can push the page load past it's limits.

Hope that helps,
Alex