A. You don't like your computer.
B. Your really bored.
Basically it edits some really important system files and deletes others. It will leave the computer you run the program on completely unfunctionable and will not boot the operating system. You might (just might) be able to recover your documents, but you have to seriously know what your doing.
And no, it won't let you boot back up in Safe-Mode.
The file is only 16kb and requires no installation. It is a simple executable file for use on the Windows NT (XP) operating system.
And no, this is not a virus.... It just simply kills your computer.