I would try thee ole method of killing exlporer.exe through the task manager then launching a new process being the command prompt then deleting it that way with dos commands.
i doubt it.. but boot up with ur windows cd. open the prompt there type in the directory and maybe u can delete it from there. kus no matter what then it wouldn't be in use.
if u tell me what the crack was (the game or a part of it or a cheat or what) ill try to help more