Are you using the online installer, downloaded from get.adobe.com/flashplayer, or the offline installer downloaded from one of the help pages?
I'd like to get some log files from you to investigate further. Please review the FAQ Where do I find the Flash Player installation log on Windows? If you're using the online installer provide all 3 files listed (FlashInstall.log, Adobe_ADM.log, and Adobe_GDE.log). If you're using the offline installer, provide the FlashInstall.log file. Upload the files to cloud.acrobat.com using the instructions How to share a document or a file sharing service of your choice. Post the link the the uploaded files in your reply.