In order to protect your device with Bitdefender Security, several Microsoft Knowledge Base packages need to be present on devices running Windows 7 Service Pack 1. You can install them via Windows Update or manually install those specific packages.
Prerequisites
Download and install the Microsoft Easy fix solution from here:
Please read the license terms and click “I Agree” and then “Next” to start the easy fix.
Install using Windows Update
Press the Windows Start 
button, select All programs, go to Windows Update and Check for updates.
Make sure your device is updated.
Manual install
Download and install KB3125574 by clicking the link below. If the link doesn’t work, try copying and pasting it into the address bar of your web browser.
Note: If you are using an older version of Windows 7 and the package above cannot be installed, you can find the proper installation packages here.