Calling Showdialog() On A Form - From The Main Form's OnLoad Event Makes The Modal Dialog Go Away After A Few Seconds?

I'm having an interesting issue that I can't reproduce on a different project, but can consistently on this one. I have no clue what might be causing it, but am hoping that someone may have seen it before.

I have a main form, from which I run a series of checks. On this form, I have a listview control. Because of some issues with the refreshing of this listview control, I had to create my own messagebox. It's just a form that displays some text ( it also happens to look nicer than MsgBox; in my opinion, anyways ). It's been working great for months, until recently.

My problem is that on my main form's load event, I run this check, which returns an error within a try/catch block. I then call my custom messagebox with a message. It in turns calls it's ShowDialog() function.

In any other situation ( after the main form has been loaded ), I have no problems. The messagebox goes on the screen and behaves appropriately ( ie: waits for my input and acts as a modal dialog ( stops execution of my main form's thread ) ). However, on this onload event, my messagebox comes up and goes away almost immediately afterwards.

I've traced it all the way to the showdialog() call. For no explicable reason, it appears to skip right over this call, without me doing anything on the form.

Here's what the inner trace looks like ( when I put a breakpoint on the onclosing event for this messagebox form ):

CODE: