Could you post your console log in debug mode to pastebin.com as you experience the error and link to it here. That will be a lot more help.
As for turning off OpenGL the only way I know of is in the game options. If this happens when you start a save and not at launch of the pack you can disable it there. If you are unable to get the launcher to start you can edit your options text file in your minecraft folder or delete it, it should regenerate with the option turned off. Be sure to backup your saves before you try to regenerate the file though.