Some files in your application depend on other files that again depend on some files.
I just found (again) dependency walker. a free tool for 32-bit and 64-bit systems.
You can find it here: http://www.dependencywalker.com/ (no strings attached).
useful tool
Re: useful tool
Dependency walker shows only a required dll files, please note, some of them could be Windows system libraries that should not be included into packing!