I agree with Alex that removing these #pragma in poppack.h is the start.
However, I'm still not ready to say "all is good again". The issue is that
we used that 'poppack.h' to build certain binaries (libraries/dlls) we
shipped. Granted the problem is less complicated when only poppack.h has a
problem. However, there's still room for problems since 'poppack.h' fails to
do what it's supposed to do. IOW, after a 'pshpack#.h'/'poppack.h' pair,
alignment does not return to its default setting... :(
There's an internal email thread currently assessing this issue and
determining how to remedy.