I have this same problem on my desktop computer (ATI display card). My monitors are profiled using Spyder 2 profiling software and when I run a slide show produced in PTE 5.0, or do a preview in version 5.0, the profile is immediately disabled. Interestingly this does NOT happen when using PTE 4.48 or playing slide shows produced in this version of the program. I would add here that PTE 5.0 is not the only program to cause this problem. I even had to turn off my screensaver for the same reason.