This obviously is a bug in Adobe Flash Player regarding memory management.

The bug seems to occur when a Flash application runs for a log time in a browser.

The bug can occur too, if there are many tabs open that contain flash content, e.g. TouTube-Videos, a painting app or music player.

Adobe knows about this issue and is working on a solution. Please always make shure that you are running the latest version of Flash-Player, which you can update for free here: http://get.adobe.com/flashplayer/