I bought this pc with the understanding that it had a valid COA. After using for a few months the notice to activate the windows 10 software was displayed for my attention. When contacting to seller they told me I had upgraded the pc to windows 10 through an update from Microsoft and it was my problem and to go to Ebay to buy a COA. Why would I upgrade to windows 10 when it was already supposed to be on the pc . I contacted the seller through email but after the first few messages they chose to ignore me.If I could have chosen no star on the overall rating I would have, but since it won't let me go on without choosing one I will select the 1 star option, although I would prefer none at all.