When you try to install Visual Studio 2012 after October 7, 2013, you receive the following error messages:
Microsoft Web Deploy 3.0
A required certificate is not within its validity period when verifying against the current system clock or the timestamp in the signed file.
These errors occur because of a failed timestamp comparison in the installer that is caused by an improperly signed Web Deploy Package.
If you receive a warning after you successfully complete the installation of Visual Studio 2012, you can fix the problem by installing Web Deploy 3.0.