We haven't heard of that issue yet, and know there are many other sites out there using Woo extensions/templates. However, it's still early in the v5.1.0 release, and possible there is a problem.
With the v5.1.0 release, we moved to using jQuery and Bootstrap Javascript files. Your template and those modules most certainly use jQuery and possibly Bootstrap, and having JFBConnect also include them may be the issue. In the Configuration -> Misc section of JFBConnect, we have easy options to disable both, and that's where I'd start.
Also, please note that the SCLogin module also has reasons to include those files and has it's own options to disable as well. Those options have been in the Login module since March though, so they may already be disabled on your site if you've been using that module.
Let me know if that has an improvement on things. If not, we'll do some testing later today to see what may be the conflict. If it doesn't work, can you explain a bit more about 'kills all modules'? Is there an error, blank space, page won't load, etc? That will really help us narrow down things faster if necessary.
Thanks,
Alex