Craven san, here's the latest weirdness (NB: my computer is fucked up on all sorts of marvellous levels, but I doubt that could be affecting this, since the reported forum time has nothing to do with my PC's clock anyway & besides my PC clock is correct)..
When I took that screenshot, A2K was reporting the current forum time as Mon Jul 21, 2003 6:03 am (exactly 16 hours after when it was saying I last logged in). Problem is, I just closed IE & opened it again (effectively logging out & back in) about 30 seconds before receiving that message (hence only 2 new posts). My A2K time zone is & always has been set up correctly (GMT +9), so it has nothing to do with that.
Weirdly enough, and possibly related, the "Logout" link does not log me out at the moment. The link simply sends me to the forums/index.php page, still logged in. However, if I close IE then open A2K again, the "last visited" time on the home page will again offset itself to exactly 16 hours before the last time I logged in.
I've double-checked & reproduced what I'm saying here about 20 times since then & now (6:39 AM GMT+9). The home page is currently saying I "last visited on Sun Jul 20, 2003 2:37 pm", which is exactly (to the minute) 16 hours before the last time I opened this site.
edit: typos fixed