userform problems with copy/paste and drop-downs
 

I created a series 19 userforms that the user will scroll through to
enter data. After pilot testing the form, this comment was made:

"Sometimes when we click back to the forms after reviewing and copying
information, we are no longer able to paste content into cells or
access pull-down menus. When this occurs, we need to open and close
the program in order to get this to work."

Any idea what could be going on here?

Thanks.