If you install an older version program in Windows 7, Program Compatibility Assistant may notice you if there is a problem and offers to fix it the next time you run the program.And Program Compatibility Assistant will block this program from running if the compatibility issue is serous.If that happens you will see below window popped up.
But in some special cases ,we may need to disable program compatibility assistant,that’s easy,see below steps
1.Click Start Button,type services.msc in search box then hit Enter
2.In the right pane,scroll down and find Program compatibility assistant service,right click it and select Stop to disable it temporarily .
3.If you want to disable PCA completely,right click Program compatibility assistant service again ,click Properties ,change Startup type to Disabled ,then click OK
Note:Above steps works in all version of Windows 7,if you have windows 7 professional or higher version of windows 7 installed ,you also can disable Program Compatibility Assistant via Group Policy Editor,