I have just noticed that I am unable to upload anything in any of my browsers (Chrome, Firefox, Safari.) I have tried various sites such as Youtube, Sendspace, Mixcloud etc and the progress bar just hangs at 0% and then eventually stalls with an error. I have only just noticed this, but it may have been like this for some time. I am running OS X 10.8.3. I have tried searching on Google but "can't upload" is too vague. I believe I have the latest version of the Flash plugin, I'm not sure what other plugins may affect uploading. Anybody got any ideas?