Anything placed on stage automatically disappears

Hello all,

I am a new-comer to these forums, as I am still trying to get used to Flash CS4.

This seems like a very simple problem (might not even be a problem at all), but I can’t figure out for the life of me.

Everytime I open up a new window, and as I randomly begin to draw in pencil or make rectangles, when the focus on the window is changed to somewhere else my drawings just disappear. Does anybody know why that is?