Windows firewall can't change some of your settings Error code 0x8007042c.

Error code 0x8007042c is an error for "The dependency service or group failed to start".
This will indicate that there may not be a problem with the Windows Firewall Service (MpsSvc) but instead with other Services that it needs so that it can start itself.

So here are the necessary Services that Windows Firewall needs on Windows 7:
1. Base Filtering Engine (BFE)
2. Windows Firewall Authorization Driver (MPSDRV)

The two services/drivers should be started or running. BFE can be easily seen through the Services Console. But MPSDRV is not visually available in the same console window and instead available only by querying the service in a Command Prompt window.
Repairing services and drivers can be done via the command line of SFC /SCANNOW on an Elevated Command Prompt.
If the command did not fix the issue then reinstalling the drivers might be the best way to do it.
Although to accomplish this will not be an easy feat since both the Base Filtering Engine and Windows Firewall Authorization Driver could not be reinstalled on Windows 7 unless we repair install the Operating System.

Try running the following commands if SFC /SCANNOW did not resolve the issue with the Windows Firewall:
1. Open a Command Prompt as Administrator. To do this, type CMD in Start Search from the Start Menu. Right click on the result and choose "Run as Administrator".
2. Run now the following command lines:
          a. netsh advfirewall reset
          b. net start mpsdrv
          c. net start bfe
          d. net start mpssvc
          e. regsvr32 firewallapi.dll
3. Confirm any boxes that comes up by clicking OK. The result on the last entry should say that  it succeeded.
      Note: If you receive any errors on any of the command lines, then there is definitely something wrong with any of the drivers and service.
              This may indicate a Registry error or a Corrupted file.
4. Reboot the system.

Another factor to consider is Malware infection. There are known strains of Malware infections that may stop or corrupt the entries and executable files of Windows Firewall along with other services and drivers it depends on.