I had the same issue on Linux on three different versions of Chromium
13 and 14. I could sove it as I described here:
The problem [...] is solved by first removing the extension, then
revoking access on twitter options, closing chromium/chrome (not sure
if this step is necessary), then reinstalling the extension and only
then authorizing it on Twitter. If the extension is reinstalled
without revoking access on Twitter options, the problem pesists.
https://github.com/cezarsa/silver_bird/issues/317