I'll try to help you as best i can.
Go to your combat arms folder, usually C:\Nexon\Combat Arms
Inside that folder you have a folder called "HShield" - This is where Hackshield stores everything.
From there go to the folder called "Update" and run the .exe "autoup.exe"
It'll open up a program, you just need to hit the "Start Update" button that appears.
Once you've done that, try running combat arms again.
If that does not work then do the same thing, but instead of going to the Update folder, run "HSupdate.exe" from the HShield folder.
Hope i helped.