This is a reply to the thread
http://groups.google.com/group/Gmail-Users/browse_thread/thread/9c839...
because of Google's absolutely idiotic policy of disabling replies to
conversations older than 60 days (
http://groups.google.com/support/bin/answer.py?hl=en&answer=46488).

So I had the same problem: the time of my e-mails in Gmail was ahead 3
hours, even though my Windows time zone was correct. I had the Google
Account time zone set correctly (http://email.about.com/od/gmailtips/
qt/set_time_zone.htm), but that was simply ignored by Gmail - I set it
to a wacko value, re-logged into Gmail, but the timestamps were
unaffected.

Someone suggested running `javascript:new Date()` in a browser tab.
That displayed a time 3 hours ahead, which made me realize that I
hadn't restarted Firefox since my trip to New York, which is 3 hours
ahead of US/Pacific.

So the solution is to set your system's timezone correctly, then
restart the browser.