When I export my movie file, the blacks turn to greys and the whites turn to light greys.
If I do PNG compression, the contrast stays the same, but then I cannot hear any sound in Windows Media Player. Other players keep delaying the video for some reason. The above picture is what it looks like in AE, and if I export wiht PNG compression. The below picture is what it looks like if I export with any other compression type.
I need a .mov file, unfortunately. And preferably able to run sound in Windows Media Player (otherwise I get delay, and some scenes are timed to music).
Any ideas? I'm using default settings, apart from the export type and compression, and +audio.
What version of After Effects are you using?
There's a notorious QuickTime issue that is always my first suspicion when I see a question like yours. Here's the link, in case you're using After Effects CS3: