FIX: A database is marked as suspect when you update a table that contains a nonclustered index in SQL Server 2005
Source: Knowledge Base
Product: Microsoft SQL Server 2005 Enterprise Edition, SQL Server 2005 Standard Edition & SQL Server 2005 Enterprise x64 Edition
Notification Contents: New and Major Modifications
FIX: A database is marked as suspect when you update a table that contains a nonclustered index in SQL Server 2005
http://support.microsoft.com/kb/934734/en-US