Did you try:
When you first start Limewire, click on the main tool bar:
Tools--> Options-->in the options box at the bottom left click on +Advanced to expan the fields. Now, click on Systme Start up.
Look for the box that says: Run on systme start up. DESELCT IT! click on apply.

Rebooting won't start limewire.
Once you do activate limewire, and then close it, it will stay on-line. In this case right click on the Limewire icon in your bottom tool bar and click exit.