Minecraft Error message 1706

My Grandson right clicked Minecraft icon on desktop to open app, but instead of clicking on OPEN, he clicked on next option down, which is Run as Administrator. This was some weeks back, and ever since we have a message appearing daily on screen regarding Media Gallery, which reads: Click ok to try again, or enter an alternate path to a folder containing the installation package 'Media Gallery x64.msi' in the box below. The box below has details beginning: C:\users\admini~1appdata\local\temp etc., This is followed by the following message: ERROR 1706 VALID SOURCE COULD NOT BE FOUND FOR PRODUCT MEDIA GALLERY. THE WINDOWS INSTALLER CANNOT CONTINUE. I would appreciate any assistance in having this problem sorted. Thank you.