I have a serious problem with my .Net program. It calls a native dll, and then crashes instantly because it can't find a native method. This is behaviour we have seen before, whereby the C# compiler, in its infinite wisdom, sets the flag that the program is DEP compatible, even if it calls a native dll which patently is not.

We have the standard workaround for this, where the flag is set to Not DEP Compatible in a post-build step, and this works fine. Everywhere except on my machine. I have Windows 7 32bit, and the program works fine on the Win 7 64bit machines that we have, as well as on Vista and XP; we have not yet been able to check on another Win7 32bit.

However, on my machine the DataExecutionPolicy_SupportPolicy is 0, i.e. we have successfully switched DEP off. Does anyone know whether there is some situation in which it can still act? Or any other mechanism which could have the same effect?

The dll in question also works fine when called from a native program. We are running out of ideas... any help would be much appreciated!