Problem with website going to main_page=page_not_found

My customer's website, https://www.hillsideeducation.com/store/ seems to work ok on Firefox and IE, but in Chrome, I keep getting main_page=page_not_found. I can navigate directly to items via the categories and the pages pull up correctly, but when I try to add an item to the cart, it goes to main_page=page_not_found. It also happens when I try to login - I can input my id and password, but then when I hit Login, I get main_page=page_not_found.

I have another store on the same server and it works fine in Chrome.

The store is at 1.5.0 and I have export email addresses installed.

Probably something wrong with things you added to your site (such as custom .htaccess content) to do URL rewriting.

I haven't done anything w/ the htaccess or custom URL's- and it does work for firefox and ie - just not chrome. Can anyone try and test the site w/ chrome? And, the set up is the same for two other sites that do work on chrome. This is just bizarre.

I can verify that adding an item to the cart on your website using Chrome results in a page_not_found (doesn't happen on FireFox). I tried this on my website and had no problem adding an item to the cart. The only noticeable difference between your site and my site is that your URL includes a subdirectory while mine doesn't.

What are your settings for your admin's Configuration->Sessions?

May or may not be related, but I notice you are running this off IIS6? Is there anything in the windows event log pertaining to IIS6?

When testing in firefox w/ firebug open usually I am redirected to the shopping cart, but sometimes I was sent to page_not_found.