Press Ctrl+N to open the "New Network Connection" dialog. Using the "Host"
comboBox on the "New Network Connection" dialog, several times: add a new host
address (e.g. a non-existent one like "example.com"), press the «Connect»
button. Open the "New Network Connection" dialog again, delete the recently
added host address:
a) using Shift+Del when the popup list is seen;
b) or using the arrow keys and Shift+Del when the popup list is not visible;
Try to delete all the host addresses until the list is empty, press Shift+Del
again. Press the «Cancel» button.
Open the "New Network Connection" dialog again, check that the list is empty.
Start a new connection (e.g. an FTP one), just in case.