i can't open your attachment as I'm at work, but I'm pretty sure from your description that you do just need to delete history. make sure your model is in bind pose and then just select it and go to edit>delete by type>history.

history is just a record of everything that you have done to your model - you can see it in your channel box on the right. if you let it build up it will slow maya down. you can also select different commands that you have performed in your history and potentially change their parameters after the fact.

hope that helps...