I'm writing this in an effort to save somebody else from tearing their hair out as I have been this morning.
If you're trying to make a sheet of labels (assuming you're using the ribbon interface, go to Mailings tab, List/Label) and you wish to use an Excel spreadsheet saved in the modern format xlsx as your address data source (TextMaker doesn't seem to support xls anyway...) then make sure the spreadsheet is formatted as text.
Otherwise, when you select Database, then File, then Datasheet and click OK, Textmaker may stop responding. I'm not sure what data formats cause this behaviour (ie: Textmaker not respoiding), but formatting the cells as text seems to work ok.
