Hello guys, I'll awake an old thread because I have exactly the same problem now.
It all started when I started to play Red Orchestra 2 (Rising Storm) again after like 2 years or so.
I've managed to reinstall punkbuster after a PC reboot twice so far but I don't want to reboot my PC that often since I am running services such as http, ftp, mail and a teamspeak server on my machine.
It doesn't matter what I do, it'll always fail copying or accessing pnkbstrb.exe in C:\windows\system32 or whatever it's trying to do...
I've used Process Explorer to find any hidden handles accessing that file but there are none, nothing is touching the file(s).
I do run Windows Defender but there is no change to my problem even when it's deactivated and I don't have a firewall activated.
This is very annoying and I'm not sure what to do. Give up PC gaming completely now when such an important game feature totally fails on you? Clearly we're not alone on this one, just google the error!
I've sent a support ticket to evenbalance but I've read their crappy answers from other forum threads so I'm not getting my hopes up on that one heh, they clearly wont be able to solve our problem because they only ask you to run the pbsvc tool with administrator rights or blame a crappy firewall even though it has NOTHING to do with the error given to them...