Ok so the error message you gave is a SQL error that the database is corrupted. If you have access to your .bak file from your db you can restore it.
Can you reinstall BKUPEXEC on another machine and restore? What medium are you using to back up to?
Have you tried running setup.exe from your sql installer cd to try and rebuild the database?
Let me know exactly where you are at and how you were backing up. If your maintainance plan was creating full .bak backup you should be able to restore those no problem.