Hi Michael,
It is very hard for me to narrow this down knowing allmost nothing about your form.
I did however make a very rough test, the way I do it at work when I have something like this happening. Problems like that are allmost always caused by some init code that you need to find, and when you have found it you often find that you are missing something or can do things a little differently to prevent this from happening, even enclosing your code with in if ! DesignMode etc... especiall for all the loadcodes. In this case it is not enough to enclose the Form's Load in such an if statement.
What I suggest you do is make a copy of your project. Then open the form in question and start removing sections to find out what is causing this. I did exactly that and found that if you remove one of the tabs in the lower part of the screen, in the Purchase Details section, this stops. This wasn't until after I removed the header, the Purchases section and on the second tab I removed down there, this stopped.
Just go on like this, isolating the problem downto what's relevant and then check if there is something you can do about it. If not, you now have a very much simple project that we are more able to check for problems.
Hope this helps,
Palli