View by cover flow not working in Itunes 8.1

Hi all, I don't know what's Happened but view by cover flow has stopped working for some reason 😟. view by list & view by grid still works but when i goto select view by cover flow, all I get is a blank screen where the albums should be & a empty space at the bottom. When I first installed Itunes & Quick time, view by cover flow was working. I havent used it tho for a couple of weeks then thought i'll try it again & now nothing. Is there a fix I can try to get it back to the way it was before it stopped working? It doesn't affect the use of Itunes in any way, (I can still sync to my 32gig Ipod touch no problem) but as I do use view by cover flow, I miss it & having to use view by grid & the moment (just means a double click on the album to see the tracks that's all), Yes all my drivers & directx are up to date & Itunes & quicktime are the latest versions. Cheers