Dennis, it seems like that's a contributor, and thanks for the hard work, but it's still not working here.
Just for the record, the include guard in crt/stl.h is _STL_H_ (note the trailing underscore)
I rebuilt my PSDK/DDK tagfiles, and restarted SE, with no apparent change in behavior. I looked for additional references to vector being redefined similar to the redefinition in stl.h, and didn't locate anything that looked like it would cause similar issues. Any additional ideas?
Removing those tagfiles conclusively fixes it, and will do as a temporary workaround.