Disable "update is ready to install" message

Is there a way to disable the "updates have been downloaded... would you like to install them now?" message? I'm on v7.7.3 and it wants to update me to 8.1 which I specifically switched away from because I experienced the "super slow network speed on windows 7" problem (see other forum posts), and I found where the actual downloaded update was (c:\programdata\agns), so I deleted that EXE but can't find where the flag to show that pop-up is kept. I've checked a bunch of .ini files and the registry. Any thoughts?

Thanks!