This seems to mean that your access permissions to the internal data file is wrong. One way to correct it would be to do the following:
make a copy of your your data file in "Moneydance\Documents" folder save the original somewhere as an archive
Rename the new copy to the original (PersonalFinance.moneydance)
Then reopen MD and see if the error goes away.
I am not a windows expert by any means, but It seems that the file is not in Documents folder but in Moneydance\Documents. Maybe a windows person can advise about that location.