I use Ancestry.com for a lot of my research. The last few months I have noticed quite a change in them. Documents that I once were able to research, don't come up anymore.
Fortunately for me, I made hard copies of many important things. It just means I have to get up off my arse and look thru the hundred of copies that I have made.
I think the internet has made me a bit lazy or the fact that I am getting older and it takes me longer to do things (sigh). To have the energy back that I had even 10 years ago would be nice :)