previous order's address showing during check out

I had couple customer telling me that when they placed orders online, they saw other customer's name and address. So I did log in to my account, added item into the shopping cart and sure, at step 1 delivery information, it showed last order customer's name and address. After I click on "change your address", my own address shows up .

I updated the site from 1.5.1 to 1.5.5e, but the problem is still there.

Can anyone help? please......

xoxomeowmixoxo:

After I click on "change your address", my own address shows up . Although it's the correct name and address on "change your address" page, once I click "continue" , the last order name and shipping address is still in the shopping cart. If I go to the check out step 2, I get an error message "WHOOPS! SORRY, BUT YOU ARE NOT ALLOWED TO PERFORM THE ACTION REQUESTED." and "You are still logged in to your account and may continue shopping. Please choose a destination from a menu."

Admin -> Configuration -> Sessions
Cookie Domain
Force Cookie Use

• make sure they both say True