Just posting this little issue I had today.
Was posting to the server last night OK, server is hosed on my webspace and has worked fine for some time now. Come to log in this morning using the desktop client and all I get is a server error and there is no way of logging in, cannot get in via web either.
logged into my webspace and checked the sql database - all seemed fine. Updated desktop client, still cannot log in.
Downloaded and installed the latest server 1.0.5 in a new directory, used the same database name and the installation picked it up, updated it and now all works fine again.
I was on 1.0.3 which I had to install after a similar issue previously a year or so ago. Then however I started again with new database and set it up with better categories etc. (I may have been on 0.85 originally)
If I try to connect now with 1.0.3 it just returns a database version error so cannot go back to check anything.
So it seems to be down to the server code, but how anything could have changed I don't know. I would have compared files with my backup, but that doesn't exist :D only the sql is backed ;)
I have found now however that I prefer the web client over the desktop client as you don't get spurious can't connect errors. (sometimes takes two clicks to post an update)