Hi Rohit,
1. Which program are you trying to install?
2. Is the issue occurring only when you install this particular program?
3. Is your computer on a Domain?
This error message usually comes the program is known to be untrusted. You might be also facing this issue due to the User Account Control Settings or the Antivirus software installed on the computer. I suggest you try the following
steps and check if it helps.
Method 1:
If you trust the program which you are about to install then try to
disable UAC (User Account Control) and check if you are able to install programs on the computer.
Follow these steps to disable UAC:
a) press Windows key + X and open
Control Panel. Under User Account and Family settings click on the "Add or remove user account."
b) Click on one of the user accounts, for example you can use the Guest account.
c) Under the user account click on the "Go to the main User Account page" link.
d) Under "Make changes to your user account" click on the "Change security settings" link.
e) In the "Turn on User Account Control (UAC) to make your computer more secure" click to unselect the "Use User Account Control (UAC) to help protect your computer." Click on the Ok button.
f) You will be prompted to reboot the computer.
Note: You must restart your computer when you enable or disable UAC. Changing levels of notification does not require that you restart your computer.
What are User Account Control settings?
http://windows.microsoft.com/en-us/windows-8/what-are-uac-settings
Method 2:
If the issue persists ,I suggest you to five full permission to your user account and check if it helps.
Follow the steps to give full permission:
a. Press Windows key + R, type regedit.exe in the search box and press
Enter.
b. Right click the HKEY_LOCAL_MACHINE and click
Permissions.
c. Click on Add in Security tab and add a new group:
Everyone.
d. Select Everyone and check the option:
Full Control.
e. Restart the computer and check if the issue is resolved or not.
Disclaimer: Important this section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry
incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry,
click the following article number to view the article in the Microsoft Knowledge Base:
http://windows.microsoft.com/en-US/windows7/Back-up-the-registry
Method 3:
****Temporarily disable antivirus or security software.
Temporarily disable antivirus software or any security****software installed on your computer.
Warning: Security software can help protect your computer against viruses and other security threats. In most cases, you shouldn't disable your antivirus software. If you have to temporarily disable it to install
other software, you should re-enable it as soon as you're done. If you're connected to the Internet or a network while your antivirus software is disabled, your computer is vulnerable to attacks.
Hope this helps.
Please post back with the status of the issue and we will be glad to assist you further.