Combobox keeps resizing

I have created a combobox with a dropdown list. Every time I click the drop down button the button gets larger and the text in the box gets larger as well until it too big to read or see. The box stays the same shape and size but the button will become so large that it fills the box completely. I have looked online and seen this is a common issue but cannot seem to find any solutions. My box contains a large number of selection items and I have set it up to narrow the options based on what the user types into the box.

Is there a simple way to stop these issues?

Quote from JonathanVH

What version of Excel?

Can you just use a Forms control instead of an ActiveX control? ActiveX worksheet controls have always been a bit buggy...

Correct me if I am wrong but I dont believe I can have the same capabilities with a form control. The list populates once you start typing a name with matching options and narrows the more you type the name, It also automatically brings up the drop down list instead of having to click the button.