You cannot install programs with unsigned drivers in non-interactive mode in Windows Server 2003 or in Windows XP (840257)

CAUSE

This behavior may occur if the program contains driver files that are not digitally signed by Microsoft. You cannot install a program in non-interactive mode if the program contains driver files that are not digitally signed by Microsoft. To provide greater system stability, Microsoft provides digital signature cryptographic technology for third-party drivers and for Microsoft drivers that pass Windows Hardware Quality Lab (WHQL) tests.

Encryptions of the driver binary and other relevant information are stored in a catalog (.cat) file. A .cat file is a collection of tags. Each tag corresponds to a file that is installed by the driver package. Each driver package that is submitted to WHQL for cryptographic signing has a catalog file entry in the .inf file that specifies the name of the catalog file. During WHQL tests, a digitally signed .cat file is created that corresponds to the catalog file entry in the .inf file of the driver package.

During driver package installation, the .cat file is registered with the operating system. The operating system references the registered .cat file during the installation of driver files that are contained in the driver package.