I suspect that has something to do with the sql server and the moodle sever.
Any ideas?
http://moodle.org/mod/forum/discuss.php?d=69176
You have still some problem in database after unsuccessful upgrading...
Maybe you could try to make a fresh install and use course backup/restore to move problematic course(s) to new moodle 1.8. to find the reason (moodle should not allow you to restore non standard parts of courses)
I don't know if this is the right place to ask, I need to find discussions on getting the site wide information moved in a backup. I was able to transfer my courses/ with their students and assignments. What I lost were Bloggs on the main page, and site wide administrators.
You are right. Course backup/restore does not move administrators roles and blogs. Then there might be no other way than try to find from database (before or after mysql dump) the "old/faulty things". Try to repair tables with phpmyadmin.
The reason might be anything non standard from previous moodle versions, not only module or block (or some old folder if you have overwritten previous versions of moodle with new ones). Try to remember if you have tested some hacks or had some crashes where structure of database could have broken.