The root cause will be IO subsystem problems. Corruption is (99% of the time) the result of problems somewhere in the IO path. Check anti-virus, check drivers, check HBAs, check SAN switches, check the SAN fabric, etc....
Why on earth did you decide to repair? If the errors were recent and your backups good, you should have been able to restore fully with no data loss, and probably a fair bit faster.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability