Thanks - but actually I did all that. None of the info on the AOL web site was helpful. AOL told me they can't help - I had to call Compuserve, which I did (after Compuserve had initially told me that I had to call AOL, of course). As it turned out, there was nothing at all to be done: Compuserve had a server problem. of course, the proper thing to do would have been to post an announcement on their web site (and AOL to have done the same), which would have saved a lot of people a lot of frustration, but maybe that's just too easy.
It's working now.