VS 2010 Conversion Error When Loading Form?

My startup form displays a login box and then, upon successful login, displays a series of buttons. One of the buttons displays a form named Calculator using the following

[code]...

When stepping through the code after clicking the button that calls the above code, it gets Calculator.Show and then jumps to code on the Calculator form that fires when a checkbox on he Calculator form changes checked state, apparently bypassing the Calculator_Load procedure altogether.This eventually results in the following error:{"An error occurred creating the form. See Exception.InnerException for details. The error is: Conversion from string "" to type 'Double' is not valid."}With the IDE claiming the error is occurring on the Calculator.Show() line on the previous form. Clicking the button a second time causes the form to load as expected, with everything working corectly.The load procedure header is:Private Sub Calculator_Load(sender As System.Object , e As System.EventArgs) Handles MyBase.Load Am I missing something in here that would cause that not to fire first upon a Form.Show call?Possibly relevant is the fact that I renamed the Calculator form prior to the problem arising, but I've searched for the old name and there are no vestiges of code still referring to it by that name. I also tried renaming the form back to the old name, but that didn't fix the problem either. (Plus I seem to recall having ran the application several times after the name change before the error was encountered, so I don't think this is relevant but didn't want to leave it out, just in case.)