I have just tried to upgrade my company site (2.0.X->2.2.3) after practising on an internal XOOPS upgrade (which went very well!).
I hadn't closed the site but I get the same issues as near as I can tell as bsimm.
When I first ran the update script, I got an error in trying to create 'xoops_profile_category'. I dropped this table and another that it complained about next time and then got a white screen (even though PHP Debug is on) - might be our error_reporting setting, I knoe display_errors is set to 0 in php.ini.
So then I refreshed the site (hpfm.com.au) and I get the default starting module/block but with no menus, login etc.
When I try to go user.php, I get the expected login page, but I cant log in with any username/passwd combo. I tried to use the password reminder, but was told that the email address is unknown.
I looked in the xoops_user table and all the entries are correct down to the md5'd passwords.
I'm a bit phazed now because I've effectively killed off my web-site. I will keep looking but any help would be muchly appreciated.