Add-to-Cart getting Error 403: Forbidden

My ZenCart store has been up and running for quite some time. But this morning I suddenly got the following problem.

When Adding a product to Cart, I get the following page:

Error 403: Forbidden
You don't have permissions to access this page. This usually means one of the following:

this file and directory permissions make them unavailable from the Internet.
.htaccess contains instructions that prevent public access to this file or directory.
Please check file and directory permissions and .htaccess configuration if you are able to do this. Otherwise, request your webmaster to grant you access.

I do not know whether this is a problem experienced from my PC only, or others are seeing it too at the same time. And I don't know whether this problem is temporary.

My store: http://store.haostaff.com

In any case, I would like to understand it.

Thanks,
Jeff

check your .htaccess file and see if it has been changed?

Hi, Yellow. I am a real dummy. Could you explain a bit more ... where I can find this .htaccess file, who/what might have caused it to change, what should I do if it is changed? Are you able to add product to cart from your PC?

Appreciate your kindness.

Jeff

Check your zencart root folder (the folder you have the store), you should see a file named .htaccess, some ftp clients hide this file tho so you may need to check your ftp client manual to see how to show this file (if you dont see it)

You can copy and then paste the content of that file here

Indeed I can't see this file using FileZilla. Strange that I can't login to my webhoster's webbased FTP manager, which I alway can login, and should see all the files. This makes me suspect that something is happening on the webhost's side that's causing this problem? Hope it will come back soon.
I will ask for help again when I make more progress.

You should contact your webhost immediately regarding the matter and see what's going on.

Many thanks, Yellow. Waiting for the response from them. Your pointer is much appreciated. The site looks and works normal until one wants to buy a product! How nice is that. I have also just received a compaint from a customer who bothers to tell me.

Just to close the loop. The problem automatically disappeared. Both problems. I can also log into my FTP shell now; and in my webstore I can put product in the cart again.

This tells me it is due to some sort of server condition, that the problem appeared. I am asking the webhost to give me the exact reason for the cause.

Many thanks again, Yellow.

Cheers,
Jeff