In what way are the photos incorrect? Is it the wrong version of the photo or a completely different photo?
If completely different photos are appearing in the stream, then perhaps your thumbnails need recreating or your library needs repairing.
Select the thumbnails of the images in the projects that are having this problem and use the command "Photos > Generate Thumbnail".
If that does not help, repair your Aperture database:
Quit Aperture and launch it again, while you are holding down the key combination option-command ⌥⌘, hold the keys firmly down, until the First Aid Panel is show. Try all repair options in turn, first "Repair Permissions", then "Repair Database".
If the wrong versions of the images are appearing in the stream - what Photo Streams are you using? My Photo Stream? Shared Streams? Have you "Automatic Upload" enabled?
-- Léonie