Let me add, that at times for 5-10 minutes, ever so rarely this sort of error will appear due to the webhosting service having a temporary problem on their end, being too busy, doing maintenance, etc.
But when it lasts longer than 15 minutes, then it can be something else, and should be reported, and normally has to be dealt with through a quick database repair or other technical fix.
Well that is it for the technical information.
Thanks for the patience with any difficulties.