Best answer by Gina
Thanks for writing into the help forum and sorry to hear you are having trouble uploading. Internet speed can definitely have an effect on this, have you changed your internet provider or settings lately? Or, are you now uploading larger files? One trick with larger files, is to leave everything on the upload page blank (except for the title) and don't click 'Save' until transcoding has started. You can add more details to the track after it has fully transcoded and been saved to your profile.
Lastly, you can always try some basic browser maintenance. Clear your cache and cookies, make sure your Flash is updated, close the browser and start with a fresh window. Also, give other browsers a try.
I hope that helps!