"Installer information msi was rejected by digital signature policy"
You get this kind of Errors when you are installing .msi File, and the installation will be cancelled. It may be on XP,Windows Server,Vista,Windows 7
To rectify this error you need to install a HotFix by micrsoft.
go to the below location and download the HotFix and install it , after installing it Reboot the system , it MANDATORY
and now install your .msi file.
I got this error when i was installing Windows Mobile Professional 6.0 SDK Refresh on Window server 2003, i installed the HotFix and its worked like Charm.
Have any issue , post here