Test Complete sometimes says waiting for the window to activate.

I developed the functional test. It executed fine for some time but when i go back after a while and try to execute, it is giving me problem saying waiting for the window to activate. and doesn't run. so I basically try to scroll the page up and down to continue with the testing.



I rerecorded it, runs fine for some time and again after a while same issue. The problem is i don't know at what point of step will i get this issue. I am getting at different points of step each time.



Please suggest what to do to activate the window .