ecomconv - 12:18 am on Sep 28, 2011 (gmt 0)

Have you tried to look at other possible issues with your store:
- issues with the site search engine for the store,
- payment systems,
- integration with the shipping carriers,
etc.
It seems there could be issues with those pieces also.
The shopping would have no effect if any of these pieces have downtime or issues.
Cheers,
dan