programs
from changing the same data at the same time. For example, if
you open a database in the browser and make a change to the database
and have not yet pressed the "save" button in the browser, the 
browser "locks" the database file and keeping any other program
from accessing the file. In particular, your Python program
will not be able to access the file if it is locked.<br />
<br />
So a solution is to make sure to either close the database browser 
or use the <b>File</b> menu to close the database 