I have become somewhat obsessed with trying to figure out why I cannot drag/drop or move the thumbnail pages on one of my two desktop computers. And I think that it is probably a problem that is outside of the Adobe program. So, I am looking for an answer from anyone who has had the same or a similar issue that I am pretty sure is related to a conflict between Acrobat and Windows 10. First, I have two desktops and one laptop. I am running Windows 10 Pro on all of the computers. After first posting my issue, see above, I then downloaded the trial version of Acrobat Pro DC to both of my desktop PC's. I have Acrobat Pro 11 on the laptop. Here's the issue: on my main desktop, I cannot drag/drop, move any thumbnails for any PDF documents using Pro DC. With the same documents on my 2nd desktop using Pro DC, I can drag/drop, move all thumbnails. With the same documents on my laptop using Pro 11, I can drag/drop, move all thumbnails. (Note: this has nothing to do at this point with security issues and access or size of the PDF in the window; all criteria are met and successful on two out of three computers with only the main desktop being unable to drag/drop, move thumbnails.) I have also completely uninstalled Pro DC, used Adobe Acrobat's cleanup tool, and reinstalled Pro DC on the main desktop, but still no success at dragging/dropping, moving the thumbnails. If there is some component of Pro DC that is corrupt and not allowing me to drag/drop, move the thumbnails, does anyone have any idea of how to remove and reinstall the component? Is there something I can edit or repair in the Windows 10 registry? (Note: I even swapped out my graphics/video card and experimented with a higher end card but that did not work either.) I think that there is something that is definitely a conflict between Acrobat and Windows 10 on my main desktop, but I'd sure hate to do a completely clean install of Windows 10 and re-installation of all my programs just to find out if Pro 11 or Pro DC will work properly with the thumbnails. (Final Note: Every PDF I open on my 2nd desktop or laptop allows me to move the thumbnails. When I open those same documents on my main desktop, the thumbnails are not movable at all. Go figure!) Anyone have this same or similar experience? Have you resolved the problem?