When applying output sharpenining in CS5, PK Sharpener gets hung up creating the preview image. Instead of appearing almost instantly, it appears very slowly, block by block, and takes a long time berfore I end up cancelling it. CPU usage is very low while this is happening. My images are not all that huge, perhaps 24 megapixels at 32 bits. I hyave tried the usual fixes - restart CS5, reboot - the problem persists. Any ideas?