Hi,
The cart works by adding a cookie to the PC with a cartid for the DB. because it's working on FF I very much doubt any scheduler job is doing this. there is the delete cart scheduler jobs, which clears the DB of old carts, but even if you've set this up wrong, I doubt very much if it would be running constantly between 3 and 10.
As I said in the previous post, I think you best option is to fix those JS error before anythign else. Maybe even remove the google stuff, this error could be stopping the cookie from being saved on the PC and hence, no cart. It could also be that the error is based on connection to google, so something could be stopping the connection between those times??
This is all very odd and it's difficult to guess what's happening!...but I think your first option is to make sure you don;t have any JS errors on your page.
Dave.