I'm aware the server has been up and down more than a politicians rent boy (allegedly ).
I've just found the problem........YAHOO SLURP.....the Yahoo search engine spider, throwing in 100's of searches a second. As Yahoo supplies less than 1% of traffic, that's a bit of liberty, so I've set it up so they can only scan 1 per second from now on.
On top of that, the server is having another GB of memory added in the next 24hrs.