For whatever its worth, I had Microsoft Security Essentials report a similar thing on my recently installed 0.9.1 on Windows x64.

Detected Item
Virus:BAT/Dakuma.1935

Alert level
Severe

Category: Virus

Description: This program is dangerous and replicates by infecting other files.

Recommended action: Remove this software immediately.

Items:
file:C:\Users\*\AppData\Roaming\Bitcoin\chainstate\313280.sst

Get more information about this item online.