sometimes, when I download an rmxp game and try to open it with rmxp, I get an error message that says "Cannot read hero class." Why?
Your data got corrupted. Might have happened during the saving of the project. Check out the Data folder if there is a Actors.rxdata. Make a backup copy and try to put in a clean one from the System folder where RMXP is installed (or just from a new project).