Adrian,
I don't know what side of the streets this one is on but I figured I would throw it at you any way. (Like you don't have enough already.[:D])
I have experienced a problem a couple of times when making kinda lengthy responces to posts. I almost lost the posts because I got the standard I.E. page saying the page I was looking for was not there and to check my network settings. Luckily I can normally tell when this is going to happen because of the long search/load time that I do not normally get and I am able to copy/paste to get the post up. But I figured I would let you know.