I found this to be an issue as well. The fix for my computer was to enable all permissions for authenticated users for the drive my dreams were installed on. I did this under the user I was logged on. Then I unchecked pause dream when windows are maximized (Single Monitors only) under the advanced tab. Finally I installed sharky's advanced codecs. This corrected the freezing problem for me. It also ensured max compatibility for mpg, mpeg, avi and wmv formats.