"Gustav G." <gaga6 / gmx.de> writes:

> Thanks for the answer, but I'm using a Windows 2000 system.

system "rasdial /disconnect"

Look here:
  http://www.microsoft.com/technet/treeview/default.asp?url=/technet/prodtechnol/winxppro/proddocs/rasdial.asp

-- 
eban