Ok, so I recently tried swapping one of my spells with with Glitchy's Model Editing Suite (MES). I used the endcode from the spell URL at WoWhead.com. I swapped and clicked "SAVE", then I closed the program and tried to enter World of Warcraft, come to find out that I constantly got an WoW Error. When I remove the MPQ file from my Data folder I don't get the error anymore.
Please help me with this. Any response appreciated.