Why is the top of this form hidden at runtime?

I have a form that, at design-time, looks like this:

...but, at run-time, has its top section winchestered:

It's not unique to this form, either - there are other instances in this Windows CE project where the same thing happens. What could cause this? What is the remedy?

It is not something with the username textbox specifically, because the bottom part of it does display, as can be seen. The "giant cursor" there is suspicious, though - why is that there, and how might this "Winchester mystery cursor" get there/be removed?

UPDATE

Here are some of the form's properties and settings that may or may not play a role in this Winchesteredness:

FormBorderStyle == FixedSingle
AutoValidate == EnablePreventFocusChange
FormFactor == WebPad
Skin == False
AutoScaleMode == Dpi
AutoScroll == True
WindowState == Normal
ControlBox = True
MaximizeBox == True
MinimizeBox == True
Menu == mainMenu1
TopMost == False

...but I don't know which, if any, of these, may be fouling me up. They are all set to their default values, so I wouldn't expect such, but obviously something winchestery is going on here.

I found out what it was:

Menu == mainMenu1

Once I removed that unneeded menu (which is added for some reason by default when adding a new form to the project) the Winchester factor disappeared.