This one's nasty.

Someone, at some time, made changes directly to the system tables in SQL 2000. SQL 2000 didn't check for that when it ran checkDB, so it went unnoticed. SQL 2008 does, but it's incredibly hard to fix.

Two options:

1) Script all objects, export all data, recreate the database.

2) Hack the system tables in SQL 2008 (no, sys.tables, sys.objects and sys.columns are not the tables). The system tables are completely undocumented, if you make a mistake you could make things worse, and making the changes will leave a permanent record in the database that someone fiddled with the system tables. CSS may refuse to help you if you have problems in the future.

Given that you also have an IAM error (same kind of cause), I'd go for option 1 if it were my database or a client's database.