If you installed KDE in ubuntu (GNOME based), you may have noticed that when you log back into GNOME, you keep the KDE cursor theme. To fix this, use update-alternatives like so:

0025|z@zentury ~$ sudo update-alternatives --config x-cursor-theme
There are 7 choices for the alternative x-cursor-theme (providing /usr/share/icons/default/index.theme).
 
  Selection    Path                                     Priority   Status
------------------------------------------------------------
* 0            /etc/X11/cursors/oxy-white.theme          50        auto mode
  1            /etc/X11/cursors/core.theme               30        manual mode
  2            /etc/X11/cursors/handhelds.theme          20        manual mode
  3            /etc/X11/cursors/oxy-white.theme          50        manual mode
  4            /etc/X11/cursors/redglass.theme           20        manual mode
  5            /etc/X11/cursors/whiteglass.theme         20        manual mode
  6            /usr/share/icons/DMZ-Black/cursor.theme   30        manual mode
  7            /usr/share/icons/DMZ-White/cursor.theme   50        manual mode
 
Press enter to keep the current choice[*], or type selection number:

press “7″ for the default