What steps will reproduce the problem?
1. Enter Combat
2. Have someone whisper you while WIM is hidden

What is the expected output? What do you see instead?
When the person whispers you, the addon creates an error, and there is no longer any whisper ouput in teh chat frames

What version of the product are you using?
Latest available (3.1.1)

Do you have an error log of what happened?
Date: 2009-06-28 18:05:12
ID: 2
Error occured in: Stubby
Count: 2
Message: Error: Original call failed after running hooks for:  ChatFrame_OnEvent
 ..\FrameXML\ChatFrame.lua line 2507:
   attempt to call method 'AddMessage' (a nil value)
Debug:
   (tail call): ?
   ...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:265
      ...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:238
   ...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:291
      ...s\WIM\Libs\LibChatHandler-1.0\LibChatHandler-1.0.lua:279
AddOns:
  Swatter, v5.5.4293 (WombatII)
  Ace2, v
  Ace3, v
  Atlas, v1.14.1
  AtlasBattlegrounds, v1.14.1
  AtlasDungeonLocs, v1.14.1
  AtlasOutdoorRaids, v1.14.1
  AtlasTransportation, v1.14.1
  AucAdvanced, v5.5.4293 (WombatII)
  AucFilterBasic, v5.5.4293 (WombatII)
  AucFilterOutlier, v5.5.4293.2531
  AucMatchUndercut, v5.5.4293.2531
  AucScanData, v5.5.4293 (WombatII)
  AucStatClassic, v5.5.4293 (WombatII)
  AucStatHistogram, v5.5.4293 (WombatII)
  AucStatiLevel, v5.5.4293 (WombatII)
  AucStatPurchased, v5.5.4293 (WombatII)
  AucStatSales, v5.5.4293.2842
  AucStatSimple, v5.5.4293 (WombatII)
  AucStatStdDev, v5.5.4293 (WombatII)
  AucStatWOWEcon, v5.5.4293.2530
  AucUtilAHWindowControl, v5.5.4293.3311
  AucUtilAppraiser, v5.5.4293.2530
  AucUtilAskPrice, v5.5.4293.3175
  AucUtilAutoMagic, v5.5.4293.3142
  AucUtilCompactUI, v5.5.4293.2530
  AucUtilEasyBuyout, v5.5.4293.3583
  AucUtilFixAH, v5.5.4293 (WombatII)
  AucUtilItemSuggest, v5.5.4293.3108
  AucUtilPriceLevel, v5.5.4293.2545
  AucUtilScanButton, v5.5.4293.2530
  AucUtilScanFinish, v5.5.4293.2530
  AucUtilScanProgress, v5.5.4293.2530
  AucUtilSearchUI, v5.5.4293.3655
  AucUtilSimpleAuction, v5.5.4293.0
  AucUtilVendMarkup, v5.5.4293.2530
  Babylonian, v5.1.DEV.130
  BeanCounter, v5.5.4293 (WombatII)
  BonusScanner, v5.0
  BrokerBonusScanner, v1.2
  Carbonite, v3.13
  CarboniteTransfer, v1.01
  Configator, v5.1.DEV.130
  CurseProfiler, v
  DebugLib, v5.1.DEV.130
  DoTimer, v4.3.5
  ElkBuffBars, v2.2.4-149
  Enchantrix, v5.5.4293 (WombatII)
  EnchantrixBarker, v5.5.4293 (WombatII)
  flagRSP, v1.0.8
  FlightHUD, v0.8.6
  Flightmap, v
  GuildMailbox, v0.0.2
  GuildPoints2, v2.0
  GuildRecruiter, v1
  GuildReminder, v1.2d
  Informant, v5.5.4293 (WombatII)
  LibSharedMedia30, v3.0-56
  Necrosis, v3.0 (r221)
  Omen, v3.0.7
  Outfitter, v4.7.3
  Prat30, v3.2
  Prat30HighCPUUsageModules, v
  Prat30Libraries, v
  Recount, v
  RPMode, v1.0
  sct, v6.2
  sctd, v3.1
  SharedMedia, v3.0.1-177
  SimpleActionSets, v0.70b
  SlideBar, v5.5.4293 (WombatII)
  Stubby, v5.5.4293 (WombatII)
  Titan, v4.2.5.30100 - Revision 273
  TitanAmmo, v4.2.5.30100
  TitanBag, v4.2.5.30100
  TitanClock, v4.2.5.30100
  TitanCoords, v4.2.5.30100
  TitanGoldTracker, v4.2.5.30100
  TitanGuild, v3.6d[QuickFix2]
  TitanLootType, v4.2.5.30100
  TitanPerformance, v4.2.5.30100
  TitanRegen, v4.2.5.30100
  TitanRepair, v4.2.5.30100
  TitanVolume, v4.2.5.30100
  TitanXP, v4.2.5.30100
  Tongues, v1.0.4.10
  WIM, v3.1.1
  WowLua, v30
  XPerl, v3.0.3c
  XPerlArcaneBar, v
  XPerlCustomHighlight, v
  XPerlParty, v
  XPerlPartyPet, v
  XPerlPlayer, v
  XPerlPlayerBuffs, v
  XPerlPlayerPet, v
  XPerlRaidAdmin, v
  XPerlRaidFrames, v
  XPerlRaidHelper, v
  XPerlRaidMonitor, v
  XPerlRaidPets, v
  XPerlTarget, v
  XPerlTargetTarget, v
  XPGetter, v1.6.2
  (ck=af3)

Please provide any additional information below.
I am going to reinstall WIM and see if that helps