why sometimes plbt iso show boot error after pressing usb choice

[jraju]

Hi,
                         This is a kind of boon to those whose pc is older and did not have the option of booting from usb. This really works of course. But, if you try to check and re boot after loading the os, due to error messages, then pressing usb reads the usb but there is some boot manager error, or other boot error messages, that bcd is corrupt or so.
                                    I think that this does not touch or corrupt the boot sector files found in the usb. It only makes menu to access the usb for those pcs which do not have usb in boot priority menu in their bios.
                        expert users, i want to know repeated use of os, for not installing or for any missing load drivers, which requires duplicate or triplicate use of the OS in the usb, gives boot error. Does this program touch and make changes in the boot files in usb.