Combo Box won't let me select items in Item List

Hi there, I'm working on a form in Acrobat Pro 9.4.4.
 
I have a combo box, and some of the items in the Item List have an export value to populate a text field on the form. However, when I go in to try and select one of the combo box items in the list to either change it or its export value, the cursor, or highlighted item, just jumps back to the first item in the list (I'm in the Options tab in the Properties menu). I can't even use the up/down arrows on the keyboard to select the item I want to change. The first time I made changes to this today, I had to delete them all and add all new items/export values. This is rediculous!
 
I can't figure out why it won't let me select individual items in the list. Has anyone had this problem or know of a way around it? Thank you!!!