Fixed now, sorry again, I forgot to tell Arnold the Db password.... and I was cream crackered yesterday so had sodded off to bed by the time MEM had died. Again.
Jo - currently, MEM is on a Virtual Private Server, i.e. just like a real one, only faked inside a bigger one. The problems are somehow related to the MySQL database & SMF forum software. I had the occasional hard crash when it had just 1 forum on; adding MEM has just made it 100 times worse...
So, the plan is, to find a web host (rather than a dedicated server), with sufficient space for all the attachments, etc., and to move MEM to that. Unfortunatley, it takes time to sort out, which I don't have at the moment. There will be a money cost, but it's minimal and I can deal with that easily.
Currently, I am thinking of staying with Daily, but buying their lower cost web hosting deal, which gives us loads of space, a control panel, and hopefully a lot less crashes (and proper support if it does crash...)