What class are you playing when the error occurs? (Rogue, Druid, Mage, Any/All, etc)
Rogue

What region version of the game do you use? (US, Chinese, German, etc)
US

What steps will reproduce the problem?
1. Installing the addon
2. Logging in
3.

What is the expected output? What do you see instead?
Expected output is for the Addon to function. Instead, Addon throws an error message and breaks completely.

What version of the product are you using?
RoguePowerBars 4.0.1.1

Do you have an error log of what happened?
Date: 2011-02-25 09:59:51
ID: 1
Error occured in: Global
Count: 1
Message: ..\AddOns\RoguePowerBars\RoguePowerBars.lua line 1004:
   bad argument #1 to 'gsub' (string expected, got nil)
Debug:
   (tail call): ?
   [C]: gsub()
   RoguePowerBars\RoguePowerBars.lua:1004 RemoveSpaces()
   RoguePowerBars\RoguePowerBars.lua:1028 BuildDefaults()
   RoguePowerBars\RoguePowerBars.lua:83
      RoguePowerBars\RoguePowerBars.lua:82
   (tail call): ?
   [C]: ?
   [string "safecall Dispatcher[1]"]:9:
      [string "safecall Dispatcher[1]"]:5
   (tail call): ?
   ...ns\RoguePowerBars\Libs\AceAddon-3.0\AceAddon-3.0.lua:340 InitializeAddon()
   ...ns\RoguePowerBars\Libs\AceAddon-3.0\AceAddon-3.0.lua:428
      ...ns\RoguePowerBars\Libs\AceAddon-3.0\AceAddon-3.0.lua:421
AddOns:
  Swatter, v5.9.4961 (WhackyWallaby)
  RoguePowerBars, v
  BlizRuntimeLib_enUS v4.0.6.40000 <us>
  (ck=61)

Please provide any additional information below.

Addon fails even with no Swatter running. BlizRuntimeLib_enUS is not disablable. Addon doesn't even show up in the list of Addons in the interface menu, nor is it invokable via /rpb.