It's a memory issue. From what I am seeing it's because you are entering raids right as the site is renewing its cache for raids so a ton of memory is used all at once, causing the mysql server to go out of memory and restart which causes the site to not be accessible until the restart is complete.
The cache is currently set to 86400 seconds from creation to when it refreshes. I had it set at one point to where it would divide up the raid recache over a period of time early in the morning but that got reset at some point to where it does all raids at one time. In the cache management you can manually clear each individual cache entry or you can do just what is expired or you can globally clear all cache entries (bad!). Clearing all cache entries at once forces the site to run a cache renew on everything and it runs out of memory every time. Then 86400 seconds later it does the same thing, out of memory and so forth. The raid caching is what is mainly causing it to run out of memory because there are so many entries and data behind it.
I'll just consolidate more expansions and this should clear up.