The problem seems to occur when you spend time moving around fully ajax sites that contain one or more iframes (I've seen this on GMail as well). In my case I worked around this issue by not using iframes but I imagine that's not always possible. Anyways, this is now Chromium bug 30693.
Wednesday, December 23, 2009
I've been seeing some odd behavior in Chrome - occasionally browser history would get hosed pretty badly. When I noticed the same issue navigating the website I'm working on, I ended up spending a bunch of time trying to get to the bottom of the issue. Initially I suspected it was something wrong with the site, but I was eventually able to create a stand-alone repro for Chrome (v3 and v4) as well as for Safari (v4). I suspect this might be a WebKit thing, which both browsers share, but I don't know enough to be certain.