I never had this problem before, but nowadays adding images is getting pretty irritating.. No image can be added from my computer, whether I try the browser upload or the Flash uploader.. All it says is IO error. Can’t figure out what the problem is.
Hmmm, sounds like a technical problem. Try to use a different browser like Google Chrome or Firefox. Also, make sure that you will try again later, after a while maybe it could be ok. Tell us how it goes!