Too-wide an index WILL NOT cause this error. SQL does not cause its own corruptions.
Too-wide an index will just cause inserts to fail. (and an insert will not partially complete)
If you're getting frequent corruptions, there's likely something wrong with the hardware. Drives, caches, something like that.
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