Need a bit more info, please. Which bottom toolbar? What's the toolbar called?
In general, all toolbars are dockable. If you wish for your layout to remain the same the next time you start a UG session, go to Preferences -> User Interface then select Save layout at exit on the dialog that pops up. This will force the toolbars to remain at their last position when the UG session was ended.
The problem is when you are picking an icon and miss it an hit the handle of the toolbar and it moves. This happens with the horizontal ones more often than the vertical ones. As a result, they can be hard to reposition.
What I mean on the bottom is the quick launch area, by the Start.
Only thing I can suggest is to be a little more careful when clicking on an icon. I know the toolbars are finicky at times when trying to dock them, but I don't seem to have trouble with them moving as you describe.
If it's getting to the point of being anti-productive, then log an ER with GTAC.
