Returning customers have old order in shopping cart

Hello
When returning customers place new orders their old order does not appear in their shopping cart on the Shopping Cart Page but once they reach the last step of the Checkout process, Order summary, there their old order is then added and they are unable to remove it.

I presume it is happening when the customer logins in and is pulling in their previous order which is not being removed.

Has anyone had a similar issue or any ideas how to resolve or investigate closer? I cannot recreate the issue my self so its a bit hard to debug.

Thanks.

Does anyone have a solution to this issue? I've got exactly the same thing happening on a 1.5.4.1 installation

Does anyone have a solution for this issue? Got the same symptoms on a 1.5.4.1 installation...