The program will not close when trying to exit using File -> Exit LibreOffice using a mouse. Ctrl+Q and clicking the X will properly close the application. This seems to have been introduced in 5.1.0 as 5.0.4 works fine. Affects both 32 and 64 bit. I am running the application on a Acer TMP278 in Windows 7.
It works for me under Win8.1x64 using LibO 5.1.0.3 and 5.2.0.0 alpha did you try resetting the user profile? https://wiki.documentfoundation.org/UserProfile
*** This bug has been marked as a duplicate of bug 97761 ***