Having some troubles booting planetary annihilation through steam, can boot regularly if I launch through PA.exe but PAMM launches through steam so im having some troubles...
I'm not sure if this will work as Steam uses it's own libraries as far as I know, but PA requires dlls from DirectX 9.0c (or rather Coherent does). Could you try installing DirectX 9.0c?
Weird... I don't have Windows or Steam, so I searched around a bit to possible causes for this and all I found was this: http://steamcommunity.com/discussions/forum/1/864975026896460782/ Basically, the error you describe can happen it Steam runs in compatibility mode somehow. That might be what is happening, because as you said, PA.exe runs fine outside of Steam.