Wanted to give a try and :
Your bug report sucks :(
What were you doing? What version of WoW are you using (1.12, 2.0, enUS, enGB, frFR)? What version of Grid are you using?
It's probably this buddy deleted the TBC folder altogether and put ## in front of everything related to TBC in the toc...like I did, and then there were tons of errors of this kind throwing onto my face telling me to reinstall Grid immediately.