Have you tried the same thing with a more modern version of AE? Adobe has a free demo of CS5.5 if you want to try it out.
I installed AE CS 5.5, went through the same process - same exact thing.
Maybe you or others could repeat this little test on your system. I can supply you with a couple of 80KB TIFFs.
By the way the project working space makes no difference between SD and HD, it's the HDTV Simulate Output preset that seems off.
My display is calibrated, and that's irrelevant anyway - the pixel value that AE shows should be the same for both comps.
Not really... You are introducing your color profile twice by assigning it twice.
Where am I wrong, then?
My workflow was the display calibrated to sRGB, source clips get the correct tags, project working space conforms all comps to one color space, and Simulate Output translates it for the display.
Are Project Working Space and Simulate Output mutually exclusive?