This is good question,
We also met some user in Indonesia have the same problem as yours. During the user start up the Point Blank game (contains HackShield) then the PB game didn't started.
This only happened on Windows XP SP3, but not on Win XP SP2 and Win 7.
I am not sure what is the caused of this issues, but if you using avast version 5 there is no issues such as this shall happened during game online startup.