Hi Nicolas,
I Have checked the database issue and, as a test, manually ran the database update sql to ensure the issues I was getting were not as a result of any permission issues in MySQL. I reinstalled 1.5.6 on the shop which is running in Joomla 1.5 latest version. Now, if one puts a SINGLE item in the cart and goes to the checkout page and then clicks the delete button to cancel the item the system immediately creates the order and moves one on into the payments page - the item in the cart is not deleted. Clicking the CONTINUE SHOPPING button also immediately creates the order and moves on to the payments page.
If one has multiple line items in the cart and then goes to the checkout page - any attempt to remove an item from the cart on the checkout page simply causes that line item to be duplicated. Clicking on the CONFIRM button duplicates all line items in the cart and does not go forward to the payments page.
The issue is only evident on the CHECKOUT page - the cart handles products correctly on other pages.
NOTE: (I have just upgraded the whole site to Joomla 2.5 and now have the live shop running on version 1.5.3 without problems - upgrading to 1.5.6 on this live version produces the identical problems I am getting on the Joomla 1.5 version which I have kept as a backup while I make sure all is good with the migration, so whatever the issue it is affecting both Joomla versions. )
Rgs
Chris