If you received the error Installation files are not signed during program installation, then perform the actions given below.
Check the system date on your computer. If the system date is set incorrectly, set it right and try to install the application once again.
One of a possible reason of the error can be out-dated information about Trusted Root Certification Authorities in Windows XP.
In this case you need to manually install the update for Root Certificates for Windows XP [May 2013] (KB931125).
Note, since KB931125 update is an optional one it can be not installed via Windows Update by default.
Users of Windows XP/Vista are recommended to perform the following actions:
For users of Windows Vista:
For users of Windows XP:
If the error occurs during the following installations, contact Kaspersky Lab Technical Support via the My Account service. In your request give detailed description of the problem. You can find detailed instructions on how to work with My Account in FAQ for My Kaspersky Account.
How to install Kaspersky PURE 3.0
Release of antivirus database updates (required to protect your computer/server/mobile device)
Providing technical support over phone / web
Release of patches for the application (addressing detected bugs)
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