Mircosoftpowerpoint.exe is a file that is created by a virus named w32.USBWorm. This virus is an epidemic and spreads very rapidly through USB drives. When a USB drive is connected to a computer which is already affected by this virus, it gets affected. The virus in the computer will transfer all its files into the drive.
Ubuntu installation on a system which already has other operating systems is simple. Ubuntu will automatically detect other operating systems already installed on the computer and enable booting into them from the grub boot menu. However if you install Windows on a system which already has Ubuntu installed on a partition other than the partition on to which you install windows then you will inevitably lose the option to boot into the Ubuntu installation. There is a simple way to rectify this issue.