For error 131131 - I was able to figure out that Security Update for Windows (KB917422) is the update that conflicted with Punkbuster. Once I removed it, it worked.
api = A set of routines that an application uses to request and carry out lower-level services performed by a computer's operating system. Also, a set of calling conventions in programming that define how a service is invoked through the application.
I will let you try and figure out what to do next :)
1. Open directery
2. Select 'Enemy - Territory'
3. Press right mouse button
4. Select 'Delete'
5. Get a life :D
I will let you try and figure out what to do next :)