@Yuliya You can reset the program settings by deleting the MusicMaker.ini file in the folder C:\Users\YourUserName\AppData\Roaming\MAGIX\mm30. Maybe this will help.
The freezing problem is caused by technical changes inside the program beginning with the new update version 44. Contact customer service at infoservice@magix.net to and ask for a patch to solve the freezing problem. They will give it out to users so you don't need to wait until the next official patch arrives.