Did you install from the original World of Warcraft Disk(s) (4 CD-ROM / 5 CD-ROM / BattleChest DVD / Retail DVD / Online Installer)
Did you have the WOTLK patch 3.0.3 Installed(this is the current patch all users should have installed) If you are getting this error please tell us exactly what and how you have installed World of Warcraft, this information is important as it will narrow down what may be the cause. This is an error that we would like to have more information as it's a particular error that has only just appeared in the last week or so.
You would only need to upgrade your account to TBC to gain access to the TBC content (if you had 3.0.3 installed) If you have or had version 3.0.3 installed on your system before you decided to upgrade your account to Burning Crusade, you shouldn't need to install TBC as this data was included in a migration patch released last year (2.4.3 - 3.0.1)
