I'm having the same problem, and it is quite annoying. Here are some additional things I've learned.
I did not have the problem on older versions of mandriva compiled kernels
It is a problem with X as it happens with the login manager
when installing I did not see a green cursor in the display setup test/preview, but now if I change video drivers, all tests/previews show this green cursor. This is presumably because the installation used a different kernel.
I would prefer not to compile my own kernel, but maybe someone can suggest a pre-compiled rpm kernel available in the normal mandriva sources that would solve this problem. Or perhaps someone knows of a different solution.