I have the same problem on Chrome on windows. I also get "Invalid Token" error when using other browsers. I found that closing the browser and opening to clear session cookies sometimes helps - but it gets pretty annoying.

I, too, am on a Mac OS 10.6 running Safari 4.0. I have also gotten that message, but only once when I had multiple login windows open.
I've not had a problem since them.  (not sure if that was the issue)

Mine were with either Safari or Chrome open exclusively and only one tab logged into the site. It only happens on the first log-in. Once I am in, it does not appear again as long as the browser window is open. Once I close the window again, I get it on the first log-in only.

bob wagner wrote:

I, too, am on a Mac OS 10.6 running Safari 4.0. I have also gotten that message, but only once when I had multiple login windows open.
I've not had a problem since them.  (not sure if that was the issue)

I always suspected there was something "off" about you and now I know why--Mac.