can anyone plz fill me up with the details about how this tool works? i know it exploits a problem with the Windows operating system which is the protocol that microsot uses to share files and printers, but how it really works??
what's in this packet that shutsdown the OS?

simple google search will answer it.

I think that this particular issue is relatively old.  The Microsoft fix for this is MS02-045 (Unchecked Buffer in Network Share Provider Can Lead to Denial of Service (Q326830)), which is available at http://support.microsoft.com/kb/326830.
 
Here is some of the requested information about how it works:
http://www.windowsecurity.com/arti [...] _Ease.html