Windows Minimize on their own

Hello,
When I return to my computer after an absence my windows have become
smaller. The little double window icon ("restore down) is showing, so it
would seem that the window is already maximized, but it's not. I have to
click the restore down button, window becomes a little smaller, maximize icon
shows up, then I have to click it again to get it to actually maximize. It's
an annoyance. Could this have to do with my photo gallery screensaver? I
hope I'm being clear and someone can help.
Thanks.