The issue would be how you're splitting the lines of the file in the first place. As you haven't shown us how you're doing that, we can only guess. Assuming that you have you just want a one-to-one mapping of lines in the file to items in the drop-down list, this is the most sensible way to load the data:
I've done some reading - someone has suggested I feed the reader into a TextBox first (a hidden textbox) and then into the Comobobox, but this doesn't seem necessary.
Is there a way I can simply knock off the last character displayed of every item in the Combobox, when it lists them in the drop down?