I do believe I tried that and it had the same outcome, though I will try again tomorrow when I visit her.
I'm also going to try installing with Windows in Safe Mode.
Yeah, try that first.
If it doesn't work, try this:
Performing a Clean install of Flash Player on Windows:
If you get to a point in the process where you're not able to proceed (you lack permissions to delete something), that's a good sign that the filesystem is corrupted.
Check for and repair any errors on the hard disk. Disk corruption can be a good indication that the disk is dying, so before you give it a good workout, you might want to back up anything critical (pictures, documents, etc.). If you're doing it on the cheap, dropbox and google offer free cloud storage.
Check your hard disk for errors - Windows 7:
At that point, reboot and try to delete the thing that you were stuck on. If it still won't delete, this utility usually gets the job done for me:
After installing Unlocker, right-click on the file and choose Unlock, then delete it. That was probably the corrupted file that was giving you problems.
Once you've finished the clean uninstall, then just download a new copy of the installer and run it:
Hopefully that gets you going. Good luck!