Clear your cache and cookies, close and restart your browser, and try again. fasttech uses cookies to remember who you are and keeps items in your cart until you return and either remove items or checkout.
Also, if you're using Microsoft's InternetExplorerExploder, stop.
Go get Firefox or Chrome, and protect yourself.
Agreed. Screen lockup is rarely the fault of a Vender/cart but rather internet connection interruption or Browser hang.