What steps will reproduce the problem?
1. Download and enable newest version of SpamSentry
2. Download and enable newest version of WIM (v3.0.6 10th of March)
3. Enable the Example Spam Blocker filtered by level in WIM
4. Have someone whisper you = immidiate error.

What is the expected output? What do you see instead?
Expected output: incoming whisper
Instead: error

What version of the product are you using?
SpamSentry - Anti goldspam 20090223

Do you have an error log of what happened?
Error occured in: Global
Count: 1
Message: ..\AddOns\WIM\Modules\WhisperEngine.lua line 279:
   attempt to index local 'win' (a nil value)
Debug:
   [C]: ?
   WIM\Modules\WhisperEngine.lua:279 CHAT_MSG_WHISPER()
   SpamSentry\compatibility.lua:31 handler()
   SpamSentry\core.lua:416 CallChatEvent()
   SpamSentry\core.lua:319 ChatFrame_MessageEventHandler()
   SpamSentry\compatibility.lua:31
      SpamSentry\compatibility.lua:30
   (tail call): ?
   ...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:252 popEvents()
   ...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:146 Release()
   WIM\Modules\Filters.lua:243 CHAT_MSG_WHISPER_CONTROLLER()
   WIM\Modules\Filters.lua:148
      WIM\Modules\Filters.lua:118
   WIM\Modules\Filters.lua:188 callback()
   WIM\Libs\LibWho-2.0\LibWho-2.0.lua:483 RaiseCallback()
   WIM\Libs\LibWho-2.0\LibWho-2.0.lua:407 ReturnWho()
   WIM\Libs\LibWho-2.0\LibWho-2.0.lua:742 ?()
   WIM\Libs\LibWho-2.0\LibWho-2.0.lua:753
      WIM\Libs\LibWho-2.0\LibWho-2.0.lua:752

Please provide any additional information below.
I also posted this on the WIM forum, found here http://www.wimaddon.com/forums/index.php/topic,726.0.html