If the installer generator portion of LabVIEW is not executable it may be because of a dll not being registered. You should try registering it by running regsvr32 on it, the dll (mergemod.dll) should be in the program files\national instruments\shared\installer folder.
If this doesn't work you can try to open the installer generator and see which subVI is not runnable, by openning labview\project\wininstall.llb\Win Install Create.vi.