Here’s a way to resolve IE9 shopping cart errors.
TECHNOLOGY Critics may disagree  but Microsoft says Internet Explorer 9 (MSIE9 or simply IE9) is more secure than predecessors so naturally, anyone using Windows Vista or Windows 7 who qualifies will give it a try. The problem is that many of these users soon discover incompatibilities with websites. Items added to shopping carts may vanish or online banking may keep returning to the login page. Fortunately, there may be a simple fix for this phenomenon.
Have Some Cookies
Nontechnical users trust others, perhaps an IT department, to set up their computers. When performing their own software updates, they often leave default settings intact. If they're extremely cautious about security, they might disable all options that transparently store information—even on their own computer.
The default installation of Internet Explorer 9 may have taken an overcautious approach by assuming that users wish to have browser cookies disabled. So what is a cookie? A cookie is not inherently bad. Basically, it's a small piece of data sent from a website and stored in a user's web browser while browsing a website. Authentication cookies enable web servers to know whether the user is logged in or not. 
A small piece of data sent from a website and stored in a user's web browser.
Here's how browser cookies work in the context of online shopping carts. You visit an item page and add it to your cart. This creates a session. A unique id number is temporarily stored on your computer so you can add additional items and checkout even while other users are shopping. If cookies are disabled, each item added to your cart may be assigned a different session id. Or when you checkout, information added to one page will not pass validation because when the server looks in the cookies to see if fields have been completed, undefined values are returned.
Those who are curious about what data is stored may examine browser options to view (or delete) cookies for every website that has stored them. Each bit of information has an expiration date. During the checkout process at Store.ClinicalPosters.com, nonessential cookies last the duration of the session or perhaps a day while others are stored up to two weeks. This permits a user to return later and finish an uncompleted shopping session without reentering prior information. (Separate and distinct from cookies, every website logs IP addresses to track potential abuse.)
Now that you know why cookies are necessary for sites that involve secure transactions, here's how to enable them in Internet Explorer 9:
- Click on Tools.
- Select the Privacy tab.
- Click on the Advanced button to open "Advanced Privacy Settings."
- Accept and allow all session cookies should be checked.
Actual steps may vary depending on browser version. You can even allow cookies on specific websites. [3,4] Sidebar video demonstrates how to adjust security settings for Internet Explorer 9 on Windows 7 with a slider. What has been your experience with Internet Explorer 9 or other browsers when shopping online? You may test to see if your cookies are configured properly by adding items in our online store.
- Internet Explorer 9 (IE9) Review. PCmag.com
- HTTP cookie. wikipedia.org
- How to Configure a Browser to Accept Cookies. [video] ehow.com
- How to Prevent Tracking Cookies in Internet Explorer. ehow.com