Cart is acting funny

[NavyChief]

I am trying hard to order a bunch of mods (may be the list below but the problem with your cart makes it hard to know)...

Shipwreck
Skinner
Server Panel
Defendable Bases
Pocket Zipline
Armored Train
Sputnick
Cargo Plane Crash

What is happening is the cart empties OR errors and empties before I can even check out...

I cannot trust the cart now....  and I cannot order them.

I even tried to order from one seller at first to see if that is the issue and ti failed... I will try another browser but if I cannot order then this site becomes useless

PLEASE HELP

[Death]

Are you using Firefox by chance?