Chromium 4.0.249.78 (36714), Arch linux, installed a week or two ago (so pretty much the latest)
Works perfectly; it's just you.
Have you tried sending just a plain text file of maybe a KB max to yourself? Perhaps google is blocking whatever you're trying to send; have you done the same in firefox? Or on a different operating system?
... wait, this is HN, not a Chrome support site/helpdesk. Perhaps you should ask them? Submit a bug, try to reproduce the issue on another system, etc.