When i try to create a WMV file PP 1.5 tells me that i cannot audio upmix. I know what Audio Upmixing is, but i'm not doing it. The wierd thing is that i try it again, and a few attempts later it lets me export. what is going on? anyone else have this problem. I have a mono audio track, a stereo master, and exported stereo. Is this mono screwing me up? I've done mono like this before with out a problem. why now?