You'll get that a lot if you rotate your logs too frequently. I see that on a lot of our stores, and the logs rotate daily (because the stats program keeps the stats).
ShopSite stats are pretty useless anyway, for any real analytics. Check out Google Analytics (
www.google.com/analytics) or use AWStats or another good stats program provided by your host.
I vote for Analytics though, the conversion tracking and other features are amazing and it's free.