The Digital signature of installation files is missing application installation error may occur if software restriction policies are incorrectly configured in the operating system. If this error occurs, configure the software restriction policies.
To configure software restriction policies in Microsoft Windows XP:
In the Start menu, select Run.
In the Run window that opens, in the Open field, enter secpol.msc and click OK.
In the tree of the Local Security Settings window that opens, select the Software Restriction Policies node.
In the right part of the window, double-click the Trusted Publishers service. The Trusted Publishers Properties window opens.
In the window that opens, for the Allow the following users to select trusted publishers setting, select the End users value.
To save changes, click OK.
Run the Kaspersky Fraud Prevention for Endpoints Setup Wizard again.