Debian normally don't show progress in the bar after the 33% it is an old graphic bug, if the hard disk is a large one and you are formating a large partition it may take some time, but it will finish without problems in most cases.
You can hit alt+F4 to see the text mode screen you can get more info there, alt+(F2-F3) will drop you into a console and alt+F1 to go back to the installation screen.
Regards
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