Download Processing Orders

[addlink]

Hi,
I'm running ZC V 1.3.9f.
I have 19 MP3 download products averaging 5 MB each.
I have never encountered problems with the download process for customers. Today for the first time, I did.
For the first time ever, I had a customer attempt to add all 19 half-hour MP3 files to their shopping cart at once.
After they entered all their information, on checkout they encountered what appeared to be an endless loop of some sort.
It read:
Loading ...Updating countryAuthenticating your informationLogging you inAuthenticating your information.Securing your information.Updating your information ...Updating your information ...Updating order total ...

After waiting several minutes for this to finish, when it did not, they eventually abandoned the attempt to complete the order.
Was this due to Zen Cart processing the large download order, or is it likely the server hung and chocked on the 19 products?
Or was it following its normal processing and they just didn't wait long enough for it to finish its thing? They never did get to the download page for the 19 products. Thank you.

[DrByte]

Loading ...Updating countryAuthenticating your informationLogging you inAuthenticating your information.Securing your information.Updating your information ...Updating your information ...Updating order total ...

Those messages don't come from original Zen Cart code. In fact you won't find any of that text in any official Zen Cart files.
You must have some addons that are acting up.