I have heard of a mysterious "Apply" button concern in regards to your problem.
Try this:
right click the "start" button
select the "properties" item
select the "taskbar" tab
You will probably see that the box by the QL selection is checked, uncheck it.
click "apply"
recheck the QL box
click "apply"
do not be concerned with the "lock taskbar" box, it should be checked.
The Quick Launch TB will be there when you reboot, for some reason i have heard that this may work, ie turning off and then back on. Have never had the problem myself, but worth a try i guess.