I was summoned to my fathers at the weekend as he had exactly the same problem. After trying everything I could think of, none of which worked, I eventually gave up and used a sledgehammer to turn of DEP globally.
To do this edit boot.ini and change the noexecute option to AlwaysOff eg;
/noexecute=AlwaysOff
Not sure if you could then upgrade Flash and put the noexecute option back to the original value- interested to know the answer to this!
This was only on my fathers backup PC, so not bothered too much about any further implications - I am sure I will be summoned again if things go bad!
YMMV & Use at your own risk!