Ok, I think I understand why this is happening, but I don't know how to fix it. It may be related to me using my host's secure server instead of having my own SSL certificate. Here is a description of the problem.
When I am done at PayPal, I click on continue. This brings me back to my web site's checkout_success.php page. The URL is
https://my_hosts.server.com/~coolcree/check...d284c448459a6a7
Notice the "~coolcree" in the URL.
Now, when I click continue on this page, the URL becomes
https://my_hosts.servers.com/index.php?action=notify¬ify[]=&osCsid=64fd1e87e396231e53f84ca784d946c7
Notice that "~coolcree" is missing from the URL. Since my host has an index.php (the whois.cart pre-installation server diagnostics script) at that URL, I get the "Server Requirements Status" page mentioned in my previous post.
Why would "~coolcree" be stripped off?
I am starting to believe that this problem is unrelated to the "Server Requirements Status" problem. It appears that I keep getting posts from PayPal, but they aren't handled properly by my site. My email box is filling up with the debug emails because they keep coming at regular intervals for about 12 hours. :o My next plan of attack for this problem is to try the test panel.
Any help is greatly appreciated,
David