In previous version users have found a number of bugs of different types: 203652198175

And russian forum
659656654652579576

All issues was fixed in version 1.7.2 and in Extension 1.3.2

To upgrade from 1.7.x to 1.7.2 (and from Extension 1.3.x to 1.3.2) just rewrite all files.

To upgrade from 1.6 or older follow the instruction:
http://rukovoditel.net/new_release.php?version=1.7