gen_ml.dll (media library winamp plugin) problem is a common issue in Windows Vista. To avoid it you can:
Delete gen_ml.dll from plugins folder if you don't need it (Recommended)
Install KMP in a folder with admin rights.
Run KMP with admin rights (right click on file -> properties)
Disable UAC in Windows Vista (not recommended)
I had the problem and got rid of it by uninstaling The KMPlayer. In Revo Uninstaller and afterwards. Installed it without the winamp plugin.
I used only necessary components during the installation and it works fine.
But if it still doesn't work look here: