Hello!
I've experience the similar problem: when I open any pdf-file or Adobe Acrobat Reader DC itself, the icon for the Adobe Acrobat Reader DC on the taskbar of the Windows 10 PRO RUS x64 is replaced with the icon of the XnView application.

1) My Adobe Acrobat Reader DC is up to date, its version is: 2015.016.20039 RUS.
2) My OS is Windows 10 PRO RUS x64 (licensed, not counterfeit).
3) XnView is 2.36.
4) I've already repaired the icon cache in my Win 10, but it didn't help!
5) If XnView is removed from OS, the Adobe Acrobat Reader DC gets it's original icon for the taskbar, as expected, but as soon as I install XnView back, the icon for Adobe Acrobat Reader DC is replaced again with the XnView's icon ((
6) The same replacement of the Adobe Acrobat Reader DC's taskbar icon with XnView's icon occurs in another system with Win 10 PRO RUS x64 on board.
Can anyone, please, propose any useful resolving suggestion or I need to wait till the new version of the Adobe Acrobat Reader DC and\or Xnview?