I have successfully installed Carbide.ui 4.3 on my fully updated Windows XP Professional installed on the desktop.
I have the following problems:

1. The additional plug-ins that I install do not stay. On restarting Carbide.ui, the plug-ins disappear from view. I am at first trying to build a theme for my personal E6. However, I have seen that a particular subfolder under D:\Program Files\Nokia\Carbide.ui Symbian\eclipse\plugins\E6_1.2.0.201108261046 does have many files and subfolders.

2. Even when I have installed the plugin, created a theme and built a .sis with self-signed method, the installation on the phone completes successfully, but when changing the theme on the phone to this newly installed one, it just keeps on processing infinitely. (I will try it again after a Factory settings restore.)