I don't have bootcamp installed but my MBP was always 8 hours out if I relied on the "automatically detect..." functions. Nothing I could find on the Apple forums or the web fixed it and I suspect the problem was somehow related to the state of the battey (which is in a bad condition).
In the end the only way I could solve the issue was – whilst logged in as an administrator – to set the timezone and time manually (switch-off the automatic settings) then reset the PRAM. I then went back to the Date & Time prefs. and re-activated the automatic time and timezone checkboxes. This seemes to have cured the discrepancy, now lwts see how long for...