I work with Flash CS5.5 on a MacPro with OS 10.7.5 with a 2 x 2.4 GHz Quad Core Intel Xeon processor and 32 GB 1066 MHz DDR3 memory with an ATI Radeon HD 5870 1024 MB graphics card. When I export my Flash to a .mov file the results are cluttered with artifacts of previous frames over the current video. What causes this? And are there preferences or settings to correct it?

My coworkers on Windows-based PCs do not have this problem.