What steps will reproduce the problem?
1. Login - message appears immediately, 100% of the time

Actual functionality isn't compromised (that I can tell). Appears to be an initialization error.

Using most current -1.6.3

Error log:

Date: 2009-02-20 20:50:32
ID: 1
Error occured in: Global
Count: 1
Message: ..\AddOns\BadKitty\BadKitty.lua line 819:
   attempt to perform arithmetic on local 'Zstart' (a nil value)
Debug:
   [C]: ?
   BadKitty\BadKitty.lua:819 BadKitty_TFZerk()
   BadKitty\BadKitty.lua:537 BadKitty_UpdateMe()
   [string "*:OnUpdate"]:1:
      [string "*:OnUpdate"]:1
AddOns:
  Swatter, v3.1.11 (<%codename%>)
  WowheadLooter, v30018
  Ace2, v
  AlphaMap, v3.52.30000.Beta
  AlphaMapBattlegrounds, v
  AlphaMapCities, v
  AlphaMapExteriors, v
  AlphaMapInstances, v
  AlphaMapWorldBosses, v
  Ampere, v3.0.3.14
  AnnoyingBuffReminder, v
  ArkInventory, v3.02
  AtlasLoot, vv5.03.03
  AtlasLootFu, vv5.03.03
  Auctionator, v
  AutoProfit, v5.3
  Babylonian, v5.1.DEV.130
  BadKitty, v
  BonusScanner, v4.6
  Cartographer, v2.0
  CartographerBattlegrounds, v2.0
  CartographerCoordinates, v2.0
  CartographerFoglight, v2.0
  CartographerGroupColors, v2.0
  CartographerGuildPositions, v2.0
  CartographerInstanceLoot, v2.0
  CartographerInstanceMaps, v2.0
  CartographerInstanceNotes, v2.0
  CartographerLookNFeel, v2.0
  CartographerNotes, v2.0
  CartographerPOI, v2.0
  CartographerProfessions, v2.0
  CartographerWaypoints, v2.0
  CartographerZoneInfo, v2.0
  Chatter, v1.0
  Configator, v5.1.DEV.160
  DBMCore, v
  DoTimer, v4.2.4
  EasyMail, v
  EquipCompare, v2.15
  EquivalencePoints, v2.2.1.$Revision: 55 $
  FlightHUD, v0.7.10
  Gatherer, v3.1.11
  GathererDBWowhead, v1.0.2009-02-18
  GemHelper, v1.8.1
  ItemDataCache, v1.303
  ItemRack, v
  LightHeaded, v275
  MillHelp, v1.1.1
  MillHelpGlyphs, v1.1.1
  MobInfo3, v0.801
  Omen, v3.0.6
  Overachiever, v0.37
  OverachieverTrade, v0.37
  PitBull, vv3.2.9
  PitBullAura, v2.0
  PitBullBanzai, v1.0
  PitBullBarFader, v0.1
  PitBullCastBar, v2.0
  PitBullCombatIcon, v2.0
  PitBullCombatText, v2.0
  PitBullComboPoints, v2.0
  PitBullExperienceBar, v2.0
  PitBullHealthBar, v2.0
  PitBullHideBlizzard, v2.0
  PitBullHighlight, v2.0
  PitBullLeaderIcon, v2.0
  PitBullMasterLooterIcon, v2.0
  PitBullPowerBar, v2.0
  PitBullPvPIcon, v2.0
  PitBullRaidTargetIcon, v2.0
  PitBullRangeCheck, v0.2
  PitBullReadyCheckIcon, v2.0
  PitBullReputationBar, v2.0
  PitBullRestIcon, v2.0
  PitBullSpark, v2.0
  PitBullThreatBar, v2.0
  PitBullVisualHeal, v2.0
  PitBullVoiceIcon, v2.0
  Quelevel, v3.0.1.3
  QuestClicks, v1.08
  QuestGuru, v0.9.8
  Rawr, v3.0.3.3
  Recount, v
  SharedMediaAdditionalFonts, v1.0
  SlideBar, v3.1.11 (<%codename%>)
  SpamEraser, v
  Talented, v1.9.5
  Titan, v4.1.6.30000 (Revision 124)
  TitanAmmo, v4.1.6.30000
  TitanBag, v4.1.6.30000
  TitanCoords, v4.1.6.30000
  TitanGemHelper, v2.0
  TitanGoldTracker, v4.1.6.30000
  TitanItemBonuses, v4.1.6.30000
  TitanItemDed, v4.0.3
  TitanLootType, v4.1.6.30000
  TitanPerformance, v4.1.6.30000
  TitanRegen, v4.1.6.30000
  TitanRepair, v4.1.6.30000
  TitanVolume, v4.1.6.30000
  TitanXP, v4.1.6.30000
  (ck=9f6)