I'd try two things first, since they're both easy:
1.) Reboot and see if the symptoms persist.
2.) If they do, please temporarily disable your antivirus program, then run the installer.
I've tried a reboot and well as disabling my Avast shields, but I'm still having the same problem.
I just tried that youtube suggestion.
I selected the flash install program "Flashplayer17_ha_install.exe"
But when I select it I get the error message.
"This program must run with data execution protection (DEP) enabled.
You cannot turn off DEP for this program."
Unless you've been modifying things in the bowels of Windows, DEP should be enabled by default. If you haven't, that's pretty suspicious. I'd grab a good malware scanner like malwarebytes.org and make sure that you don't have any obvious infections.
You'll definitely want to confirm that DEP is enabled for Flash.
Please see the following Microsoft guide for instructions:
Hi, DEP is enabled by default, I was following the instructions in the youtube video that m_vargas linked.
I got another message today about there being a flash player update, downloaded again, but still the same problem.
I am having the same problem,but i have windows XP......I have tried everything......keeps saying Adobe download manager has encountered a problem and needs to close....