I only started having this problem after I activated the Falcon Engine, this site has been under development for weeks and never had that problem, but when we were done creating it. We decided to turn on the caching before it went live to speed test it, and it worked great for a day, loading in .333 seconds. Then I came back the next day and the home page was white.
It could be a conflict with another plug-in, that's why I listed them all. I've had a similar issue when using WP Super Cache with BPS Security. And I solved it by deactivating some plug-ins that were using a lot of memory.
However this site does not have any memory hogs on it that I know of. However I have gotten rid of all excess plug-ins.
But I won't know if the problem is solved until tomorrow.