this is a common issue that after a software upgrade, the installer asked reboot persistently. So what is the root issue? When the installer replace the current files with new, and it will determin if the file is in using. if yes, it will record them in regedit, like below:
When the computer reboot again, Windows will check if there is an entry, if yes delete the files in the entry and then clear the entry. And then the msiesec will check if the entry is deleted, if no, keep ask user to reboot the computer. Sometimes, this reg entry may not work as expected, like Windows can not find the file or the file is current using though everything works fine.
the solution is delete the entry.