First, make sure that you select Logitech QuickCam Pro 400 from the Video Devices list. To do so:
1. If Monitoring is in progress then on the Monitor menu, click Stop Monitoring first.
2. If a device is already in use then stop its preview. To do so, on the Monitor menu, click Stop Preview.
3. Point to Video Devices box above the Preview window and select the required video device from the dropdown list.
After the correct device is selected, turn off Date/Time Stamping.
1. On the Tools menu, click Options.
2. Under the General tab, uncheck the option "Add a Stamp on Video Recordings and Snaps".
3. Click OK.
Now try starting the device preview and monitoring.