FCKeditor doesn't work out of the box

I downloaded version 2.6 today and it doesn't work out of the box. I have tried it in Firefox, IE6 and Opera as well as on XP and kubuntu. If I use the demo from the fckeditor website or use the _samples/default.html then everything works fine. However if I go straight to the editor/fckeditor.html file then I can not insert text, buttons, tables, etc. In opera the error messages seem to be related to "Could not convert undefined or null to object". Here is a specific error as reported by Opera:

Inline script thread
Error;
name: TypeError
message: Statement on line 36: Could not convert undefined or null to object
Backtrace:
Line 36 of inline#2 script in file://localhost/C:/FCKeditor_2.6/fcked ... ditor.html
if (FCKConfig.CustomConfigurationsPath.length > 0)

Also found an error stating "message: Statement on line 105: Reference to undefined variable: FCKLang"

Any ideas on how to fix this? I'm really interested in using this software.