Sort function not working properly...

Been using this Excel form for approximately three years, haven't had any issues with it, even when we upgraded from 2007 to 2010 a year ago. But the past month the "Sort" function has started to give me issue. I highlight what I needed sorted, select to sort largest to smallest, and it goes all out of whack. Once I sort it, it decides to pull information from other cells instead. For example, under my "Total" box, for "Saturday" it is pulling a value from F18. But once I sort it, it pulls from F40 instead.

This has always worked in the past with little difficulty. Anyone care to take a look? Form attached. I had no idea how to search for this issue, so sorry if this is a duplicate. I tried Googling it, but had no luck.

Maybe lock the cell first?

Starting with =$F$18