I was just sitting here fighting with the same thing. I was first thinking maybe the issue was related to the sticky post on the media uploader, but what fixed it for me was turning deactivating all of my widgets. I then activated each widget one at a time to narrow down which was the issue. Fortunately, I’ve enabled all of my widgets and the images are still displaying.
Hopefully the deactivate/activate trick works for you too (and permanently).
BTW, the widgets I have enabled are:
Inline Google Maps
Lightbox 2
WP-Forum
WP-Forum Latest Posts
WP Events Calendar
Good Luck