What steps will reproduce the problem?
  I haven't been able to reproduce it when trying to, though according to Swatter it's happened twice today.

What is the expected output? What do you see instead?
  No specific expected output. I moused my cursor over the debuff bars (Warlock DoTs in this case) unintentionally and received the error pasted below. It's possible it was related to something other than the mouseover, as I haven't been able to reproduce it.
  At the time the error occurred, I had one mob as my focus and another as my target. I *think* one of them died before the error, but I'm not sure.
  Additionally, the depleted debuff bars don't leave the screen until the UI is reloaded.

What version of the product are you using?
  The latest version available on Curse, for the 3.0.2 patch. Release 7?

Do you have an error log of what happened?

Date: 2008-11-06 15:52:03
ID: 51
Error occured in: Global
Count: 1
Message: ..\AddOns\Quartz_Buff\Buff.lua line 743:
   attempt to compare number with string
Debug:
   Ace2\AceEvent-2.0\AceEvent-2.0.lua:737
      Ace2\AceEvent-2.0\AceEvent-2.0.lua:689
AddOns:
  Swatter, v5.1.3715 (SnaggleTooth)
  WowheadLooter, v30014
  Ace2, v
  AltBuster, v1.7
  Altoholic, v3.0.002b
  Armory, v5.1.3
  ArmoryFu, v5.1
  ArmoryGuildBank, v5.1
  AucAdvanced, v5.1.3715 (SnaggleTooth)
  AucFilterBasic, v5.1.3715 (SnaggleTooth)
  AucFilterOutlier, v5.1.3715.2531
  AucMatchUndercut, v5.1.3715.2531
  AucScanData, v5.1.3715 (SnaggleTooth)
  AucStatClassic, v5.1.3715 (SnaggleTooth)
  AucStatHistogram, v5.1.3715 (SnaggleTooth)
  AucStatiLevel, v5.1.3715 (SnaggleTooth)
  AucStatPurchased, v5.1.3715 (SnaggleTooth)
  AucStatSales, v5.1.3715.2842
  AucStatSimple, v5.1.3715 (SnaggleTooth)
  AucStatStdDev, v5.1.3715 (SnaggleTooth)
  AucStatWOWEcon, v5.1.3715.2530
  AucUtilAHWindowControl, v5.1.3715.3311
  AucUtilAppraiser, v5.1.3715.2530
  AucUtilAskPrice, v5.1.3715.3175
  AucUtilAutoMagic, v5.1.3715.3142
  AucUtilCompactUI, v5.1.3715.2530
  AucUtilEasyBuyout, v5.1.3715.3583
  AucUtilItemSuggest, v5.1.3715.3108
  AucUtilPriceLevel, v5.1.3715.2545
  AucUtilScanButton, v5.1.3715.2530
  AucUtilScanFinish, v5.1.3715.2530
  AucUtilScanProgress, v5.1.3715.2530
  AucUtilSearchUI, v5.1.3715.3483
  AucUtilSimpleAuction, v5.1.3715.3708
  AucUtilVendMarkup, v5.1.3715.2530
  AutoProfitX, v2.04
  AutoRepair, v
  Babylonian, v5.1.DEV.130
  Baldrick, v1.5.93
  Bartender4, v4.1.2
  BeanCounter, v5.1.3715 (SnaggleTooth)
  Bookworm, v
  Broker2FuBar, v1.0
  ButtonFacade, v0.1Alpha
  ButtonFacadeLiteStep, v3.0.2
  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
  ChatBar, v2.6
  ChatEdit, v2.0
  ChatScroll, v3.2
  ChatThrottleLib, v20
  ChatTimestamps, v1.6
  Chronos, v2.12
  Configator, v5.1.DEV.130
  ConsisTint, v1.1
  DBMAPI, v
  DebugLib, v5.1.DEV.130
  DurabilityStatus, v
  EasyMail, v
  Enchantrix, v5.1.3715 (SnaggleTooth)
  EnchantrixBarker, v5.1.3715 (SnaggleTooth)
  EnhTooltip, v5.1.3715 (SnaggleTooth)
  EveryQuest, v$Revision: 27 $
  EveryQuestOutland, v1
  EveryQuestProfessions, v1
  Examiner, v08.10.30
  FarmIt, v
  FBMergeDatabase, v0.9.6
  FBOutfitDisplayFrame, v0.9.6b
  FBTrackingFrame, v0.9.6
  FishingBuddy, v0.9.6c
  flagRSP2, v1.7.2
  FlightMap, v
  FluidFrames, v2.1
  FocusFrame, v2.4.1
  Friendly, v0.7.1
  FriendsShare, v
  FuBar, v
  FubarEmoteFu, v3.0.0-3.0-0.2
  FuBarFishingBuddyFu, v2.2d
  FuBarGroupFu, v1
  FuBarHealBotFu, v3.0.2-1.00
  FuBarItemRackFu, v1.1
  FuBarMoneyFu, vv1.2
  FuBarPetInfoFu, v3.0.1 $Revision: 89 $
  FuBarPointMan, v1.4
  FuBarSkillsPlusFu, v3.0.0
  FuBaruClock, v2.0.11
  GatherMate, v1.0.6
  GatherMateCartImport, v1.0
  GatherMateSharing, v1.0
  GFWDisenchantPredictor, v3.0.1
  GFWFactionFriend, v3.0
  GFWLinkerator, v3.0
  GiveMeHealth, v
  Gymnast, v
  HealBot, v3.0.2.20
  InFlight, v3.0.003
  InFlightLoad, v3.0.003
  Informant, v5.1.3715 (SnaggleTooth)
  ItemRack, v
  MapNotes, v5.11.30000
  MapNotesBrowser, vv1.00.30000
  MapNotesIconLib, v1.04.30000
  MapNotesIconLibFancy, v
  MapNotesIconLibLegacy, v
  MapNotesIconLibNeptunia, v
  MapNotesIconLibNumbers, v
  MobInfo2, v3.71
  Necrosis, v3.0 RC1
  NotesUNeed, v6.52.30000
  oGlow, v1.12
  OgriLazy, v1.1.0
  Omen, v3.0.2
  OmniCC, v2.2.5
  OmniCCOptions, v
  PartyCastingBars, v2.0
  PassLoot, v3.4
  Pawn, v1.1.3
  Planner, v
  Portfolio, v0.5
  PowerAuras, v2.5.8b
  Quartz, v1.0
  QuartzBuff, v1.0
  QuartzFlight, v1.0
  QuartzFocus, v1.0
  QuartzGCD, v1.0
  QuartzInterrupt, v1.0
  QuartzLatency, v1.0
  QuartzMirror, v1.0
  QuartzPet, v1.0
  QuartzPlayer, v1.0
  QuartzRange, v1.0
  QuartzSwing, v1.0
  QuartzTarget, v1.0
  QuartzTimer, v1.0
  QuartzTradeskill, v1.0
  QuestGuru, v0.9.5
  Recount, v
  ReURL, v2.0
  RPHelper2, v2.2
  ShieldLeft, v3.3 Beta
  Skillet, v
  Squeenix, v3.0.2.9
  Stubby, v5.1.3715 (SnaggleTooth)
  Thottbot, v
  TradeJunkie, v4.0
  TrinketMenu, v
  WhoNeedsThis, v0.31
  (ck=103d)

Please provide any additional information below.