This may be obvious, but I'm just covering the bases like a good tech support rep should: When you switch to 480p in SOCOM, the screen should flash and then it should ask again: "are you sure?" If you fail to respond, it reverts back. This isn't what is happening to you, is it?
I too have the same problem. My answer is, you don't really have an HDTV. I found out not too long ago that although some sets have the component inputs in the back, it doesn't mean the TV supports 480p. You DO get much clearer picture without the progressive scan mode but if you get a scambled picture on SOCOM when you turn progressive scan on, its just means your TV doesn't support 480p. Sadly thats how it seems to me.