I just got a call from my grandfather, and he told me that he burned through three-quarters of his 5gb hotspot data plan in one day. My thoughts are that the timing of this is all too coincidental, and that his PC may have cached the Windows 10 installation files. I'm gonna get him setup with teamviewer later this evening and take a look, but I would appreciate if anyone had some information on what I should be looking for. I believe he his running windows 8, but I'm not 100% on that.