Please help; a buy can't put his order

Could someone give me an idea/advice how to fix this issue please? The customer cannot make put his order.
He wrote this;
--------
I created an account...it keeps telling me that items with a red ! are not available....won't let me go further.
I am using a regular computer and am a repeat customer.
----------

I'd be so happy to get your advice.
Thank you.

that customer also said;
----------------
None of the products I chose had the red !.....I kept getting a message about them at the top of my screen.
---------------