Often when I go to the store and click an item in slot 3, this item gets activated. I use a resoltuon of 1280x1024. The 3rd item slot in the store windows happens to be above the inventory buttons in the game. My guess is that I'm somehow clicking inventory buttons through the shop window. I shouldn't be able to do this. It's a big problem because I keep my Shurelya's in that slot and I often need it soon after leaving the store.

I've never had the store open over my items. Perhaps click and drag the shop window to a safer location?