Solve BOOT file illegal

This may be that your boot.ini file has been deleted, copy a normal BOOT.INI file to the root directory of the C drive.

If the system is XP, you can modify it like this: Right click on my computer ——properties —— advanced, point startup and failback settings, click edit, in the open notepad Delete the original text, then copy the following content into Notepad to save and confirm to exit and restart the computer. The contents of the normal xp boot.ini file are as follows:
[boot loader]timeout=3default=multi(0)disk(0)rdisk(0)partition(1)\\WINDOWS[operating systems]multi(0)disk( 0) rdisk(0)partition(1)\\WINDOWS="Microsoft Windows XP Profession"

Save as boot.ini, then restart it will be fine, if you can not enter the system, you can also enter the editor under DOS.