Trojans are malicious applications that pose themselves as legitimate software in order to trick users to install them. Once on the victim's machine, it may run any number of malicious process to steal vital information or inflict damage to other software.
When launched, the Trojan writes a component, which when launched will cause the computer to freeze, to the file C:\No-Boot.com. It also writes the string No-Boot
to the end of the file c:\autoexec.bat.
Once the computer is rebooted, it will freeze.