I had the same issue and could not get steps 6 to 9 to work. I then thought the idea of restoring the database by simply copying it back seemed like inexperienced support help so instead I kept the clean Data folder i.e. renamed the Data.old back to Data, copied the BEDB.bak file from the DataBackup folder into it, then used the BEUTILITY.EXE program to restore the database properly from the backup. It is what it's there for.
This allowed v9.1 to contain the original data and after copying the Catalog folder across I re-ran the upgrade to v10 and all was well again - at least so far. Oh, and I did restart the SQL services just as it was about to run some scripts (I was installing to full fat SQL 2000 not the noddy MSDE version) to make sure the database was actually available when it tries to upgrade it.
I did find this strange as on another server where noddy MSDE is used it all went fine. Either the upgrade cannot cope with straight SQL server or I can only assume there was some sort of corruption in the database that the upgrade cannot handle and the restore using BEUTILITY clears it up. So much for the daily maintenance - fat lot of use that was!!!!