I suspect you have installed a version of Win32::GuiTest that has been compiled with newer version of VC++. That way GuiTest.dll will have a dependency on MSVCR80.dll or whatever version it is you are using. This will fail on machines that don't have this library installed. I think newer versions of PerlApp will automatically try to bundle any versioned MSVCRT libs, but if you are using an older PerlApp, you'll have to do that yourself using the --bind option with the "extract" suboption.

Alternatively you could install a version of Win32::GuiTest that only uses MSVCRT.dll, which seems to be the case for the package from the UWinnipeg PPM repository.