This I found via
InsideGoogle:
ry using Web Accelerator on a forum site, one with lots of geeks who love Google and probably already have Web Accelerator installed. Why, if you're lucky, you'll be logged in as someone else, as the folks at SomethingAwful.com discovered. The posters in that forum discovered that most of the times they refreshed the page, they were logged in as a different person, seeing their friend's control panel for the forums.
If Google isn't going to fix this problem ASAP, I will have to ban the IP range WebAccelerator uses