I just uninstalled some add-ons and it works, such as the mech's, firworks launcher, zelda sfx2, and truces new event mods. like ifprojectile and ifitem in hand.
Buffer overrun means you have too many addons enabled/crappy addon.
Exactly. A buffer overun means the buffer in blockland (mostly when it loads the datablocks) is overrunning, which can be caused by to many add-ons. Just go to start a game, press the "add-ons" button and put some add-ons out. The problem is fixed when you have not to much add-ons on.You don't need to completely uninstall them!