A:Answer There is an error in the Best Buy transaction processing software. I had the same problem when I tried to order this computer and I'm sure Best Buy is losing lots of sales due to this.
Best Buy sent me an email asking me to complete my order when I could not complete the transaction online. I replied using a link in the email and was able to order this computer. Be persistent. Sorry, but I don't recall exactly how I managed to order it online, but after about 5-10 minutes of messing around I was able to get it done. It was worth it because the Best Buy price is very competitive.