Comment 137 for bug 459647

I can confirm this bug in 11.04 as well using Unity and Compiz.

Here is my workaround: (I think Step 6 was last and not before #4...)
1) Manually unpack your cursor tar.gz files in usr/share/icon.
2) Log out and back in to have Natty see all the ones you just unpacked in the Pointer selection menu.
3) Go to System Settings -> Appearance -> Customize -> Pointer tab -> Select the theme you unpacked in step 1 -> Save your custom theme -> Close the Appearance window.
4) Navigate to etc/alternatives and edit x-cursor-theme. It should say:
[Icon Theme]
Inherits=NAME_OF_A_UNPACKED_FOLDER_IN_STEP_1
5) Log out and back in.
Alas, it still only half worked for me and was using an old icon set I had chosen on some pages.
6) Go to Appearances again and notice that your Theme may now NOT be selected and be Custom instead. I could not delete Custom, so selected the same icons, border window, cursors etc and saved it with the same name in Step 3 overwriting the original.
7) Enjoy.