I encountered issues when I try to update my iTunes to the latest version (as of 23 Sep 2015) but the error pop up as shown above or text below.
"There is a problem with this windows installer package. A program required for this install to complete could not be run..."
After searching, I found this solution which is to use Win RAR or 7-zip to extract out the iTunes set up installer (iTunes6464setup.exe) into a folder.
Delete "AppleSoftwareUpdate.msi" file then I double clicked the "iTunes" installer file in that folder and it worked. However, it may not be necessary to delete it I realized.