It just means that it can't find the URL for the various files in its database. Which usually means the database is corrupted somehow, even though there are several failsafe mechanisms.
As this does not seem to be a general problem, please go to %appdata% (e.g. by typing that into the Start -> Run command box) and delete the whole 'ProfitUI Reborn Downloader' folder. Just to be sure you may want to deinstall the updater and install it again.
If it fails again, I would guess that either some driver (like IDE or SATA) is having some problems or that your harddisk is near its end of life.
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