I first discussed the Windows Server 2003 Software Restriction Policies in tip 8048.
If you created a local policy at Computer Configuration / Windows Settings / Security Settings / Software Restriction Policies / Trusted Publishers, you may receive one of the subject errors when you try to install a program or update.
To resolve this problem:
1. Open a CMD.EXE window.
2. Type the following command and press Enter:
reg DELETE "HKLM\Policies\Microsoft\SystemCertificates\TrustedPublisher\Safer" /F