If you do not have the floating toolbar appearing when you hover your mouse near the right of the screen enable it by right clicking on the Vision icon in the taskbar near the clock and go up to options > show shortcut bar. If it is enabled you may need to turn it off and back on for it to display.
Hover your mouse at right top of the screen to see the Vision toolbar. The top most button of the toolbar is divided into two sections, one is a button you can click on, one expands out into a menu when you select it. Go to this menu and select ’manage classrooms’.
Once in the manage classrooms screen, click on the classroom you use the most and click edit classroom. Check the box labeled ’make this my default classroom’ and then click ok and exit the classroom manager.
Click the menu in the toolbar’s first icon again and select the classroom that you made default. It should display as bold. Once you’ve selected it, click the connect classroom button if it isn’t already selected then click on the topmost button in the toolbar to open the classroom.
After these changes it should open normally for future uses.
Note: This issue is addressed for new users in version 8.6.2, however it won’t repair the issue once it has occurred.