Sudden Problems with Paypal since Dec 1???? IPN Handler (Zen Cart v1.2.4)

Preface: Sorry if the tone of the following post sounds like finger-pointing. I don't mean it to come across that way. I haven't had my coffee yet this morning, and I'm kinda groggy. The intent behind my comments is to help point out what maybe has gone wrong and to aid you in planning your future steps.

Trinity:

Why did a module. that was installed over 2 years ago, suddenly go pear shaped?No idea.
Maybe someone changed a setting in your admin to make that module suddenly start getting used when it wasn't before?
Maybe your site has been hacked and files have been added/changed on your server?
Maybe you should treat it as though you've been hacked and do a thorough file-by-file inspection on your server until you can prove there's nothing rogue on it.

Trinity:

I downloaded this module from the Zencart web site...have never downloaded from anywhere else, but you suggested that is might have been OsCommerce code??So, are you suggesting that somehow Zen Cart is liable for something you downloaded under use-at-your-own-risk terms?
Addons submitted by 3rd-party contributors are generally scanned to check for malicious content or deceptive advertising or copyright violation. But they are not always tested on a real live shop, and not always code-inspected line-by-line before being marked as available for download.
Furthermore, if you're talking about an addon you downloaded 4 years ago, I suspect if there were a serious problem with the addon it would have been discussed on the forum somewhere and perhaps even an update posted for that addon. If you didn't update the addon with the newer version (if there was one), then naturally you'll encounter the relevant consequences.
I suggest doing a forum search about the addon you mentioned, to see what others have encountered with it over 4 years since you first grabbed an early version of it.

Now ... off to find the coffee ...

No, I am not suggesting "Zen Cart is liable for something you downloaded under use-at-your-own-risk terms". I was just trying to point out my confusion if it was an OsCommerce module then why did I find it on the Zencart site...sorry, but I was not trying to lay blame here.

As my hosting provider has confirmed there have been no changes to our site and no security breaches then I shall just assume that my Altzeimers has kicked in and I must have done something myself!...no-one else has admin access. :-)

Well, now I am confused...two days after I deleted the offending code the orders from 2nd December have started to come through??? Interesting though that the orders have todays date...

Now I am beginning to wonder if it was a Paypal issue, any insight on this is most welcome.

If PayPal saw the IPNs as failing, it would have queued them to send later.
And, yes, they'll always show up in your store as the date on which the IPN was received.

As explained here: http://www.zen-cart.com/wiki/index.php/PayPal#How_Does_IPN_work.3F

5. NOTE: PayPal's™ server will attempt the IPN notification (hourly) for up to four days if it's not successful on the first try. In this case your customer's order will not show up in the Admin until the IPN notification is successful.

Thanks DrByte!