[View Cart - Error 500]

I need a little advice.  I was checking my shop to see if everything was working smoothly and i can add a product to my cart, but when I click on view cart, it gives me an Error 500 every single time.  What can I do to fix this? 

If it helps, I am installed cubecart as an application on my godaddy account.

[Product mix and match?]

Thank you so much for replying so quickly and thanks for the warm welcome!  

[Product mix and match?]

I'm new to cubecart and I'm learning my way around it, but I was wondering get if there is a way to have a product where you offer mix and match items.

I have 6 products, but I would like those to also be offered under a 4 for $20 deal.

Any help or advice is appreciated. 

Thanks!