Update: I found the "cthub..." file on my server in a folder called "_mm". So I moved it to the root directory, and then Contribute was able to connect. The next time, however, it wouldn't connect and it was looking for a file called "contribute.xml". This was also in the "_mm" directory, so I again moved it to the root. After this Contribute was able to connect.
However, the problem now is that it cannot find homepage, because it is looking for "index.html". All of my files (created on the server of my previous host) are .htm files, and it appears that the default filename for my new host is .html. I found a help file on Adobe's website advising me to change this in the "Administer websites" dialog. But when I try to "administer" my website, I get this error message: "Contribute cannot save your changes to the website's shared settings."
Just a suggestion here, based on our experience of moving CPS to a new server. CAUTION: I would perform this knowing ahead of time all that you need to know about your new connection: the URL, what the default home page is (index.htm or index.html, the FTP connection settings, etc.). Also, be sure to back up your user xml files and other mission critical files so you don't lose them. You should be ok because you're not re-installing CPS, but it's always good to be safe.
You can re-establish your connection by removing the old one and creating a new one. First open Contribute, and even though it doesn't establish the connection, just get to the home page. Then click Edit-->My Connections to open the dialog box that shows your "old" connection. You can choose it and click the button to Remove it. Then you can click the Create button to walk yourself through the process of creating a connection to the new server.
Again, BE SURE you know everything you need to about your new connection before attempting this, so you'll know how to create it. Moving files over is not likely to help as your connection process is filled with multiple writes and reads to the server via FTP and the best thing to do is create a new connection (and a new encrypted connection key as a result) that sets this up completely. Once you're re-connected, you can get into the Admin section and enter the list of possible default files the server may be using (e.g. default.htm, index.htm, index.html, default.html, etc.) so that your home page can be recognized.
Hope this helps.
Thanks for your help. I ended up creating a new connection exactly as you suggested, and it seems to be working fine. I also changed the default filename on my server to index.htm.
Just a clarifying question on this recommendation:
Does this affect all of the existing contribute users? Put another way - will I have to re-create new connection keys for everyone?
No since you did not change anything in your website...