sporadic "empty cart" problem with file uploads

On my website clients enter 12 lines of text and upload 12 photos per order. Many clients have reported this problem:

They enter the text and photos, click "add to cart", wait for awhile and get a "cart empty" message on the shopping cart page.

It doesn't happen to everyone. Only about 1 in 25 clients. Then they have to email me the photos and text OR they have been successful entering the text and checking out without the photos.

Many prospective clients have abandoned their order after this occurs. Of the ones that send me their order by email, I have tried uploading their exact order (text and photos) without error. I have tried it on IE and Firefox.

Is this happening to anyone else? Any suggestions?

Thanks for your help. My website is mycustomstory.com if that helps.

I found the answer and thought I'd post the resolution incase this issue arises for someone else.

I had increased the file size at Admin -> Configuration -> Maximum Values -> file upload size, but did not know I also needed to increase the PHP config values. And because the message was "Your cart is empty" instead of "Your files are too big" or something else more meaningful to the actual problem at hand, it took quite a while to figure out the issue.

Here's a link to the thread that helped me:
http://www.zen-cart.com/forum/showthread.php?t=83787&highlight=maximum+file+upload

this post:> Three things:

• Admin->Configuration->Maximum Values->File upload size
• PHP configuration: upload_max_filesize
• PHP configuration: post_max_size

For your PHP configuration, you will likely have to talk to your host to ensure that the values are large enough. You can check the current PHP configuration settings via Admin->Tools->Server Info