When you manually copy files to USB pendrive or different boot medium a system will boot in installer mode by default.

Best way to avoid it is to use installer to prepare boot drives, although if necessary changing default boot menu selection is also possible manually:

Please mount USB key in Linux or Windows system and use text editor, which understands unix-like endline characters (for example notepad++). In directory /b(build number(/boot edit file:
- gen.cfg: change variable default=4.I to default=4.0.
- kernels.cfg: move line 'MENU DEFAULT' to section corresponding to 64bit system instead of installer.
Please pay attention to preserve the same pattern to avoid errors.