Can't Log In, Can't add to Cart

We upgraded to 1.3.9; cart was working, cause I was testing out coupons. But yesterday, you can't log in and you can't add anything to the cart. For trying to log in - It goes to a white screen and the url is

http://www.digiscrapaganza.com/index.php?main_page=login&action=process

For adding a product to the cart, it's

http://www.digiscrapaganza.com/index.php?main_page=product_info&cPath=20&products_id=114&number_of_uploads=0&action=add_product

I've looked high and low for a solution for someone else that has had a similar problem, but no luck. Does anyone have ANY suggestions for where to start looking for a solution?

TIA.

Start here:

https://www.zen-cart.com/tutorials/index.php?article=82

Thanks, I did find that thread. My partner and I are double checking these things now.

Hi
I am having the exact same problem on 1.3.9, I've read that thread and also tried resetting password using phpmyadmin but it doesn't work.
Can't log in to the admin and adding to cart doesn't work.
Site here: http://www.breeze-events.com/store/

Any ideas?
Cheers, Tom

Fixed it - needed to add www. in configure.pgp

http://www.zen-cart.com/showthread.php?101626-Website-address-without-www