I opened a notebook file and received the following message:

There appears to be an error in the file named below. You should close it without saving, 
then check the "Parse and load entire notebook into memory upon opening" checkbox in the Notebook Options dialog.

How, exactly, do I do the required action and what will be accomplished? The file is clearly dingged. But I cannot find how to accomplish the action. I find no evidence of the checkbox or where it might be located. Any hints would be appreciated.