Windows – “Access Denied” when accessing a web site

I am using Windows Vista IE9. I live outside the US, if it matters.

Recently, I have problem accessing www.cvs.com. I always get the message,

Access Denied
You don't have permission to access http://www.cvs.com/ on this server.
Reference #18.b83edc3d.1427525750.3f370291

I have no problem accessing other web sites in the US, such as JCPenny, Walgreen, CNN, etc. I am accessing the web sites from the network provided by local ISP.

The first thing came to my mind was something wrong with my browser. I checked. No problem I can find. I Googled the error. I got the link http://support.microsoft.com/en-us/kb/908356 which basically says I should add the URL of the web to the Trusted site zone. And I did it. Keep getting the same error.

I e-mailed CVS and asked them if they knew anything. They gave me a routine reply. Nothing helpful. I Googled around. Most of the stories I found are about the Access Denied after they did some programming. But, I didn’t do application work on my machine.

I am a regular user of Stack Exchange sites. Naturally, I come here to look for help. If my question is off-topic, please direct me to the right one. If there is a tag missing, please help me to add it. Thanks.

Update (03/09/2021)

I just test it again, instead of getting "Access Denied" message, I am getting the following message

CVS.com® is not available to customers or patients who are located outside of the United States or U.S. territories. We apologize for any inconvenience.

For U.S. military personnel permanently assigned or on temporary duty overseas, please call our Customer Service team at 1-800-SHOP CVS (1-800-746-7287) if you need assistance with your order

Thank you for all the help from the users.