I have had trouble hacking combat arms with vista but i just found out how to get chams working with Harold's bypass 2.5..
1-Download Harold's bypass 2.5
2-Go to your Combat Arms folder for me it was c:Nexon\combat arms
3-The files that you downloaded put in the combat arms folder not Hsheild or Game just combat arms folder
4-Now right click the bypass.exe and click run as administrator and then on the box that pops up press ok
5-Now you can run Combat Arms with bypass
Chams
1-Do all the steps above and run combat arms
2-When you get into a game press insert and it should work (you may have to press it a few times or hold it down)
This tutorial helped me get chams working hope it helps you