We have had 3 reports of this in the past month or so, where customers are unable to select the correct state. Every time they tab or click out of the state field, it switches to a different state. We do not have the postal code lookup enabled.
The one customer who was able to give us some details said this: He was using Firefox 37 on a Linux machine. He was trying to do separate shipping and billing addresses, and he would select Tennessee with his mouse (not sure if this was in the shipping or billing section). Then when he moved the cursor away from the box, it would switch to Rhode Island. He said it was almost like the drop-down was still invisibly open, and moving the mouse changed the selection. When he unchecked the "different billing address" box, he was able to get Tennessee to stick with no problem.
Interestingly, his order also went through with $0 shipping, but I'm wondering if that was related to switching addresses a bunch of times, and may have been fixed by the most recent live shipping snippet update.
The first two times we thought maybe the customer was crazy, but after the third time it seemed like it might be a bug of some sort. I just tried to replicate it, and I'm not getting quite the situation he described, but I realized it is confusing when you use the mouse to select a state (instead of typing). You click on your state, which then appears in the field at the top, but the drop-down list stays open and when you tab or click to the next field, it switches the selection to whichever state was hovered over last. So you can select Tennessee, then move the mouse down to Texas without clicking on it, and then tab to the postal code field, and it switches the state to Texas. You can get it to stay on Tennessee by being fortunate enough not to accidentally hover over a different state before going to next field, or by actively clicking the up arrow to close the drop-down list. I had to try it a few times before I figured out what I was missing, so I'm not surprised a customer would be a little frustrated. And unlike the one customer's experience, it does seem to be the same whether or not the different billing address box is checked.
Is there a reason for the drop-down list staying open after a state is selected, or is it a bug? The country drop-down list does close after you make your selection, which seems to be a more comforting and less confusing behavior!
Our store is at manufacturing.dustystrings.com, and we're using 2.0.