Sudden code-rot?

I ran into a really weird error today while trying to make some progress with my game.

It would just keep throwing an InvalidCallException on the Device creation in the engine. I had done no changes to the code, no nothing.


I finally found out that in the code where PresentParameters for the Device are initialized, the Windowed property is no where set to true if the app runs in windowed mode!


And it had worked before! What on earth deleted a line or just decided to require it, all of a sudden? I had installed Hitman: Blood Money, and after that I hadn't compiled the game nor ran it... and as far as I know, Hitman didn't install any new DX binaries.


The InvalidCallException isn't very helpful. Not at all. It doesn't even point out what might have gone wrong...

I know that there's the DirectX debug version and such, and I tried it, but I didn't find a way to see what kind of messages it gave. I read they could be set to be visible from project props in VS and going to debug and setting "Allow unmanaged debug" or something like that... well guess what, there was nothing like that in VS Express. Gahh.