First I want to reiterate the problem is fixed for now. So I'm only furthering this discussion as a learning process for you guys. I'm not unhappy, only confused.

Second I want to remind you that I duplicated the problem. I did it once, and it broke things. I restored the site to before the upgrade then followed the same procedure and it broke again. So I doubt it was any timeout issue or anything transient like you described.

Third I think it's important for you to know the procedure I followed. It was what I'll call the "partial uninstall" procedure outlined in this posting: www.joomlapolis.com/component/option,com_joomlaboard/Itemid,38/func,view/id,104950/catid,92/

As you can see, it tells you to uninstall some pieces, but not others. It does not work as documented, as you do have to uninstall all CB plugins before reinstalling them. That would be all the ones found in <joomlaroot>/components/com_comprofiler/plugin/user. This is what I did. However, you can reinstall the CBSubs plugins that go in <joomlaroot>/components/com_comprofiler/plugin/user/plug_cbpaidsubscriptions/plugin without reinstalling, which is what I did. The module and mambot must be uninstalled and reinstalled.

I actually think it was the PARTIAL uninstall procedure that caused the problem. I bet if you did a complete uninstall of all plugins/modules/mambots that it would work fine. But now that I'm working I don't want to break the site again just to find out.

As I said, I've moved on. I'm giving you this info for future posterity.