This is my favorite setting for Adobe Reader, because too often a PDF takes too long to load or hangs and I can’t switch tabs in my browser or it gets locked up and I have to go into the Task Manager and end the task. 
In Adobe Reader 8, go to Edit -> Preferences then select Internet and uncheck Display PDF in Browser and press OK. You may have to reboot for the change to take place, not sure why it doesn’t just change it on relaunching Adobe Reader, but that’s what the dialog says.
Unfortunately, every update to Adobe Reader will lose this setting.