The steps to follow are:
Make sure you are running the latest version of the game - fully patched. Should be v1.4 at the time I posted this.
Make sure you have updated the punkbuster files - check out the evenbalance web site for updater and instructions here
http://www.evenbalance.com/index.php?page=pbsetup.php
1) Extract the zip file (from my previous post) named CoD-WaW_Connection_Failure_Fix.zip (take note where you extracted it to)
2) Move that extracted file (named 'CoD-WaW_Connection_Failure_Fix.bat') into your 'Call of Duty World at War' install folder.
3) Double-click the file 'CoD-WaW_Connection_Failure_Fix.bat' and it will copy over the file [PnkBstrK.sys] for you into your C:\Windows\System32 directory.
That *should* work, with any luck! If it doesn't, it would indicate that you do not have 'PnkBstrK.sys'. I'll zip and attach my copy of it just in case. Extract and place it in your 'Call of Duty World at War' install folder, then run 'CoD-WaW_Connection_Failure_Fix.bat' again.
If that doesn't work, it must be yet another damned quirk with PB :-/
Good luck!