Site should now be back to normal with full functionality. Actually, it should be much better than "normal"
I will provide a full explanation once I am satisfied that our technical support staff (at the Data Centre and server administrator) have truly "nailed" the problem.
Again, I do apologise for the poor response time and very flakey service over the last few days. Obviously, I was very unhappy with what happened, but at the end of the day I do have to rely on the advice I receive from those who know a lot more than me about these matters. That said, no one predicted the massive traffic surge on Saturday which made things so much worse.
Also, for the record, this is only the 2nd time we have experienced such hardware failures. The previous occurrence was about 3 years ago (which was the catalyst in us moving from a VPS to a dedicated server)