Login with Swatter enabled.
Swatter returns error log.
Of couse, trouble disapears when disabling InstancePOI.
0.10.3

Swatter error log:

Date: 2009-01-09 08:04:10
ID: 1
Error occured in: Global
Count: 1
Message: ...e\AddOns\Cartographer3_InstancePOIs\InstancePOIs.lua line 74:
   attempt to index field 'Lvl %s Elite %s' (a nil value)
Debug:
   [C]: ?
   ...e\AddOns\Cartographer3_InstancePOIs\InstancePOIs.lua:74
      ...e\AddOns\Cartographer3_InstancePOIs\InstancePOIs.lua:65
   ...e\AddOns\Cartographer3_InstancePOIs\InstancePOIs.lua:87
      ...e\AddOns\Cartographer3_InstancePOIs\InstancePOIs.lua:85
   (tail call): ?
   ...e\AddOns\Cartographer3_InstancePOIs\InstancePOIs.lua:155 Add()
   Cartographer3_InstancePOIs\Data.lua:41 in main chunk
   [C]: LoadAddOn()
   Cartographer3\Main.lua:2912
      Cartographer3\Main.lua:2911
   [C]: xpcall()
   Cartographer3\Main.lua:2926 func()
   Cartographer3\Utils.lua:105
      Cartographer3\Utils.lua:95
AddOns:
  Swatter, v5.1.3910 (SnaggleTooth)
  Ace2, v
  Ace3, v
  ACP, v3.0.10.15
  Atlas, v1.13.0
  AtlasBattlegrounds, v1.13.0
  AtlasDungeonLocs, v1.13.0
  AtlasOutdoorRaids, v1.13.0
  AtlasTransportation, v1.13.0
  AtlasLoot, v5.02.07
  AucAdvanced, v5.1.3910 (SnaggleTooth)
  AucFilterBasic, v5.1.3910 (SnaggleTooth)
  AucFilterOutlier, v5.1.3910.2531
  AucMatchUndercut, v5.1.3910.2531
  AucStatClassic, v5.1.3910 (SnaggleTooth)
  AucStatHistogram, v5.1.3910 (SnaggleTooth)
  AucStatiLevel, v5.1.3910 (SnaggleTooth)
  AucStatPurchased, v5.1.3910 (SnaggleTooth)
  AucStatSales, v5.1.3910.2842
  AucStatSimple, v5.1.3910 (SnaggleTooth)
  AucStatStdDev, v5.1.3910 (SnaggleTooth)
  AucStatWOWEcon, v5.1.3910.2530
  AucUtilAHWindowControl, v5.1.3910.3311
  AucUtilAppraiser, v5.1.3910.2530
  AucUtilAskPrice, v5.1.3910.3175
  AucUtilAutoMagic, v5.1.3910.3142
  AucUtilCompactUI, v5.1.3910.2530
  AucUtilEasyBuyout, v5.1.3910.3583
  AucUtilItemSuggest, v5.1.3910.3108
  AucUtilPriceLevel, v5.1.3910.2545
  AucUtilScanButton, v5.1.3910.2530
  AucUtilScanFinish, v5.1.3910.2530
  AucUtilScanProgress, v5.1.3910.2530
  AucUtilSearchUI, v5.1.3910.3655
  AucUtilSimpleAuction, v5.1.3910.0
  AucUtilVendMarkup, v5.1.3910.2530
  Babylonian, v5.1.DEV.130
  Bartender4, v4.2.1
  BeanCounter, v5.1.3910 (SnaggleTooth)
  BonusScanner, v4.1
  Cartographer3, v3.0 v0.10.3
  Cartographer3InstancePOIs, v
  Configator, v5.1.DEV.130
  DebugLib, v5.1.DEV.130
  LibStub, v
  SlideBar, v5.1.3910 (SnaggleTooth)
  Stubby, v5.1.3910 (SnaggleTooth)
  Titan, v4.0.2.30000 (Revision 25)
  (ck=614)