Hello, everytime I press mouse button 4 I get a lua error. I first thought it was some kind of "micro shuttering" and that is probably how I whould best describe the (EDIT: visual) effect of pressing mouse button 4 while in normal combat. EDIT: It also lags (when pressing).

I have deleted Cache, Interface, WTF and Data\Cache folders, located in my game directory (installed at "C:\Program Files (x86)\World of Warcraft)").

When I turned on lua errors (after I deleted the things mentioned above), this is the error message I recive ("Count: 60" since I pressed Mouse Button 4, 60 times):

Message: [string "UIErrorFrame:Clear();"]:1: attempt to index global 'UIErrorFrame' (a nil value)
Time: 01/25/12 17:04:31
Count: 60
Stack: [string "UIErrorFrame:Clear();"]:1: in main chunk
[C]: in function `RunScript'
Interface\FrameXML\ChatFrame.lua:2118: in function `?'
Interface\FrameXML\ChatFrame.lua:4293: in function `ChatEdit_ParseText'
Interface\FrameXML\ChatFrame.lua:3992: in function `ChatEdit_SendText'
Interface\FrameXML\ChatFrame.lua:2704: in function <Interface\FrameXML\ChatFrame.lua:2697>
[C]: in function `UseAction'
Interface\FrameXML\SecureTemplates.lua:275: in function `handler'
Interface\FrameXML\SecureTemplates.lua:561: in function `SecureActionButton_OnClick'
Interface\FrameXML\MultiActionBars.lua:14: in function `MultiActionButtonDown'
[string "MULTIACTIONBAR3BUTTON2"]:2: in function <[string "MULTIACTIONBAR3BUTTON2"]:1>

Locals: (*temporary) = nil
(*temporary) = nil
(*temporary) = "attempt to index global 'UIErrorFrame' (a nil value)"