In the notification area on the taskbar, you double-click the Bluetooth icon, or you right-click the Bluetooth icon and select "Bluetooth-apparaten weergeven" ("Show Bluetooth Devices").
In this scenario, you expect an "Apparaten en printers" (Devices and Printers) window to open which shows the Bluetooth devices which have been paired with this computer. However, on the Dutch version of Windows 7, this window does not show any devices, even if you have attached Bluetooth devices to the computer.
This is a known problem in the Dutch version of Windows 7.
To work around this problem, click on "Apparaten en Printers" (Devices and Printers) in the address bar at the top of the folder. This will show all the devices and printers configured on the system, including the Bluetooth devices.
Note: If you have a large number of devices attached to the system, and you would like to filter this view to only show the Bluetooth devices, you can do so by clicking on the "Zoeken in Apparaten en printers" (Search Devices and Printers) search bar in the top right, and typing the following: