Quick Look not working properly since Lion update
Ever since my update to Lion the Quick Look function doesn't work properly anymore. If I want to preview say an image pressing spacebar in Finder while that image file is highlighted Quick Look window sometimes stays blank. If I close this window (spacebar) and open it again (spacebar) it might show the file, but it's not certain and AFAIK this is not the expected behaviour.
The same random behaviour occurs when navigating (arrow keys) to the next/previous image. Any ideas why?
iMac (27-inch Mid 2010), Mac OS X (10.6.8)