Excel 2003: Changing cell contents blows up User Defined Formula which uses that cell

Cell X1 has a Formula, call it FF, which uses 2 user defined formulas, MAE, MSE:
Code:

Formula:

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MAE and MSE inputs in FF are


Range RX: Col X from R2 to R500
Range RY: Col Y from R2 to R500

If I take any cell in RX and change its contents,
I get a NAME? error in cell X1.

If I click on FF, I see the formula which appears to be correct.

Some other potential factors:

• Each cell in RX is itself the results of a Formula: the Summation of 2 other Cells. Even if I double click and move the colored selection outline to another cell, FF gets the NAME? error.
  
• This worksheet used Row 1 Labels in Formulas which at some point in time were lost for some unknown reason. Labels were replaced with traditional ranges in all formulas. But this "damage" occurred many revisions ago and there did not seem to be any problems since them. Whether this could be contributing, I don't know.
  
• This workbook occasionally bombs and Excel does a recover on it.
  
• I am using a PC which is unstable which occasionally freezes every few days.

Any thoughts?

OK, how do I upload the file?

I was thinking. Isn't there a setting so that Macros update every time the spread sheet updates? Shift + F9?

Because once I make that change, if I do an Evaluate, MSE and MAE come up as NAME? which means they are not recognized. And I've verified the Module is included with their code.

I'm wondering if it is the Macro Calculation Option reverting back to MANUAL since some workbooks could have a extremely long calculation time - and it might take 1 hour to open.

So I wrote User Defined Functions. Are these treated as Macros when it comes to Calculation Options?

My guess is NO since I'm getting the NAME? error.