PayPal IPN warning!

Hi all,
I have been receiving these emails occasionally for about a week. I applied the June paypal patch, and am running the latest version of Zen.

The email reads:

Please check your server that handles PayPal Instant Payment Notifications (IPN). IPNs sent to the following URL(s) are failing:

http://toyotawheelspacers.com/index.php?main_page=checkout_process

If you do not recognize this URL, you may be using a service provider that is using IPN on your behalf. Please contact your service provider with the above information. If this problem continues, IPNs may be disabled for your account.

Thank you for your prompt attention to this issue.

Sincerely,
PayPal

The site has been up and running for about 6 months with no problems...then the emails started arriving a week or so ago. I removed both IPN and Express modules and re-installed/reconfigured them after the patch, but the emails kept arriving (about once every other night). I have a ticket in with my host and am still waiting to hear back. Anyone know what this is all about or how to fix it?
Thanks!
Also, this "error" has occured, and paypal has sent me an email when using IPN and Express. (One at a time, I did not have them both up as payment options at the same time).

this shouldnt be the IPN address

http://toyotawheelspacers.com/index.php?main_page=checkout_process

that should be

http://toyotawheelspacers.com/ipn_main_handler.php

do you use your paypal to receive payments from like ebay or other sources,
If so then it will try to access the address that you have in the IPN return address at paypal

Thanks Merlin,
At the risk of sounding like a total nub, what is the easiest way to correct this? Through Paypal, or do you modify a php file.
Yes, I do sell on ebay too and never have a problem with it.
Also, why would it just start happening within the last week and not when I first started using Zen?
Thanks again!

you need to login to paypal.com and go to profiles,

edit the IPN url, make it go to your IPN file

http://toyotawheelspacers.com/ipn_main_handler.php

I only know about thsi because I started getting them

Thanks so much Merlin, I changed it. I shall report back.

Ok, changed the URL in PayPal ... ZenCart still works fine, still processing sales fine through Express Checkout.
I did get another error email message from PayPal and it showed the old URL was still returning the error. I look in PayPal and it shows the new one I had entered into the IPN settings. PayPal tech support told me to give it 4 days and the error emails should stop ... Guess I shall report back once again.
Thanks!

After changing the URL in IPN preferences, I received the warning emails for 2 more days. PayPal wound up deactivating the IPN on my account. I simply went back into PayPal re-activated it with the proper URL still in place and no warnings since. Guess it just took some time for PayPal to "catch up". All's fine now.
Thanks again!

MysticHarbor,
Can you please send me a PM with the your PayPal account email address? I have a technician looking into this to determine whether there is a system problem that can prevent this for others in the future.