Magento

Error generated after deleting demo data.
I was testing and preparing the site for production. demo data was fine, testing the basket fuctions with a registered test client.
When I deleted the demo products and logged again with the registered test client the error below appeared.
error is:
Fatal error: Call to a member function getId() on a non-object in /home/lacave/public_html/app/code/core/Mage/Sales/Model/Quote/Item.php on line 142

I know I had 2 products pending in my basket.
This operation breaks the site if trying to log in.
I tried deleating the test client this did not help.
Any suggestions?