Paypal Problem

I have a problem setting up my paypal account. I was testing through the Instant Payment Notification (IPN) of paypal, the URL address hosted here on Dreamhost, and as it seems, Paypal is not able to call that page. This page exists and I am able to access it from any browser. I contacted paypal, they told me that my hosting company might have a proxy that is blocking them from accessing my page. My website is hosted on the ‘bonanno’ server on Dreamhost.
Hope someone can help me here.
Thanks a lot.