The half-picture thing happens a lot and is usually caused by your computer viewing the picture while it's still uploading from the camera. The Symi internet connection can be very slow at times and it takes several seconds for the picture to be uploaded to the server.
If you see just part of the image the best thing to do is wait ten seconds or so and then refresh the page by pressing f5.
If you just wait for the picture to refresh automatically it will do that in 30 seconds and is likely to grab just part of the next picture as it's being uploaded. By waiting a few seconds and forcing a refresh it gets your computer out of step with the camera so you get the full picture. So to speak.
Incidentally, I started wondering the other day just how many individual Symi pictures have been taken by the webcam and decided to work it out (I know, I need to get out more).
The camera was installed in its present location at the end of July 2008, taking pictures every 30 seconds day and night. Give or take the odd few days of 'down time' that means it's taken around 3,500,000 pictures.
That's a LOT of Symi!!