Daniel came to visit me in the office on Thursday afternoon. He helped me upgrade the ArcSDE installation. Here you can see him typing in the SysAdmin password. Things took a turn for the worse after this and we had to roll everything back to the previous version, 9.2, which we knew still worked. However, the following day we managed to get everything up by chaining the SQL DBA to the desk and not letting him go until he had entered the required password in the appropriate places. Services have resumed as normal and our users are happy again.