In desperate need of help!

I am in desperate need of help. I have installed many Zen Cart stores and enabled PayPal. I just recently did a store for a client and we had 2 people order different ways before opening and it worked fine. Then we started getting complaints that people were getting the message attached. I looked through the forum but could not find an exact answer to this issue ( this forum is a god send a lot ) Could someone please help me? Please?

I am using Zen Cart 1.5
Store link http://jolynchtubes.com/store

I do have another store installed on Host Gator and it runs perfect. Thanks for any help.

Also the clients say they are logged in the store and when we check they do have accounts.

All of the products are virtual and I did check twice to make sure Virtual product was checked.

May be improperly or incompletely uploaded files. See also this thread, especially post #21:

http://www.zen-cart.com/forum/showthread.php?t=190388

I'm not sure I understood, but downloads should not be marked as Virtual.

Thank you so much! I did #21 and someone ordered shortly after that so I am hoping that fixed it. Thanks for the help and I really did search but did not find that thread, i think i searched the wrong key words. thanks again :D