I am running Fedora 9 in VirtualBox, if that makes a difference...
When I tried to test out the new clock applet, I wanted to add my hometown as one of the locations. It asks for me to select a timezone from a very long list (which sucks, but obviously there's not a whole lot that can be done about that)... of course I wanted to get to the correct timezone as quickly as possible, so I moved my mouse slightly further down at the bottom part with the arrow for scrolling, which made it scroll much faster... only problem was, I lost complete control for my mouse at that point! I watched and waited as every timezone flew by. When it got to the bottom of the list, I regained control of the mouse. I assumed it was probably a coincidence, but when I tried to scroll back up to find my timezone, it happened again :-/
Note: problem does not occur when scrolling slowly