This is a difficult issue to explain, so please bear with me. I'm running OS X Yosemite and Parallels 10 with Windows 7. Ever since upgrading to Yosemite and Parallels 10, I'm having a strange issue in that the characters within a window screen on the Window 7 side slowly disappear. The window border remains, but portions of the characters within the window slowly disappear with an outside to inside progression. I've attached a screenshot that shows the before (top) and examples of the progression of how it disappears. This continues until the characters no longer appear. When I close the window and reopen, everything is begins fine. Up until now I have only noticed this occurring in one particular software program (DOE-2 Simulation Viewer) and it never occurred prior to the update. I know about 8 other people running this exact configuration with the same software and they do not have this issue. Any help would be much appreciated.