Check if this 'Vista BUG Confirmed SMB2 causes Index Corruption' Thread #1430067 Message #1435304 applies to you as well (you may review the whole thread).

>At one of our clients it happens regularly that the index of one table gets corrupted over night.
>
>I suspect the backup procedure which backsup open files, but they say they are using the backup for 10 years already, so why does it start happening now?
>
>Has anybody seen this happening, and what other reasons could there be?