To anyone interested.
A few days ago I came up with this error.
" Script 'game_interpreter' line 455: TypeError Ocurred. no implicit conversion from nil to integer "
I tried a few things, from uninstalling and re-installing video/audio codecs, RTP RPGmaker, Visual Basics, deleting some registry that where related to the game as well as some .dll files of the root folder but with no success. This afternoon however, I installed CCcleaner and did a Registry Clean, and when I tried restarting the game, it stopped giving me the same error. I don't know if that was the solution, but you can try it and report back if it works or not as I don't know how to trigger the error again to check it myself.
I suppose you can use other methods to clean the registry, but I only know about CCcleaner.
Hope it helps. -best regards.