When I post an image to my blog, I don't use thumbnails very often because they are too small and just post the original sized pic. However, when I enter the description (which is correctly generated by WP within the 'alt' tag) it doesn't show when you mouse-over the image. It only seems to work if you use the thumbnailed version.
I stress that this is only within Firefox as IE7 shows the descriptions all the time as it should.
Does anyone have any idea why this is?