Yea i get the same problem as well. It was working fine earlier yesterday then poof, I would start a mission and I would just a have a camera angle of the map (a preset one by the way, don't know if that helps) and couldn't do anything. The mission plays (I know this because when trying to play EagleWing, the "Bohemia Interactive Presents... A bonus Mission" text comes up, but nothing else), but I'm viewing something completely different. I'm at a loss as to what could be causing this or how to fix it. I haven't re-installed either Arma2 or OA yet because of what Thegazman said. I'd rather not have to take the time to do a clean wipe and re-install.
Windows 7 64bit
Intel Core i7 2600k @3.4GHz
Radeon HD 6870
8GB RAM