Is LW only starting up the once, when you turn on your computer? In LW tools > options > advanced > system startup. Untick 'run on system startup' > apply > ok

If LW's always popping up & won't stay closed, that's a whole other problem (worm). If it's not doing that, ignore this! If it is doing that, check out this thread.
http://www.gnutellaforums.com/showpo...88&postcount=2