You can't set master to single user mode and you don't need single user mode to run a normal checkDB.

I'm running SQL Server 2000 and according to the error log I need to run the command DBCC CHECKDB against a database while it's in single mode. If the database is set to multi_user the error shows in the log.

Why are you running repair? What's damaged? Do you know what repair will do?

I'm running the command to check for data integrity, I'm hoping nothing is damage and the DBCC CHEKCDB hopefully will tell me that.