In order to try and reduce the amount of data being transferred to search engines (Google accounts for around 6GB per month of Forum data alone!) I have added some last modified handling. Hopefully this won't impact the everyday use of the site, but if pages start not refreshing please let me know so I can look into it.

One thing I've noticed since your tweak, is that threads don't show as "read".
Where they would normally go to white text in list once I'd read that topic, they now stay as unread for a strangely random amount of time???

Odd, it's not doing that to me in IE7, whether I click the back button or go to the Forums link again. What browser are you using?

Firefox 3

It literally started doing it the other day.

I've been having this problem for months in FF3

strange thing was... and spooky it is to... (cue "Twilight Zone" music) after my last post in this thread went to topic list AND it showed THIS topic as read.
Huh?
Last night it took nearly 3 minutes just for the LandRaider topic to show as read.
Go figure

I'm using firefox 2 and it's just started doing this.

I think I'm going to have to revert the caching handling then, as it appears to be causing problems. What I'll try and do first is enable it only for identifiable spiders and see if that helps to reduce bandwidth and still allow the site to work for members properly.

UPDATE: I've modified the caching code so that it only sends the Last-Modified header, and performs the additional checks to see if a check for the modified date is the request, if the User Agent for the request indicates it's a Snap, Google, or Yahoo request. This should mean that the forums work as they did before I made the changes for requests that are not for these search engines.

heh, you haz a gremlin in teh mainframe.
Apparently for this site only, I don't get automatically redirected after posting

Nope my bad. It's a setting in FF3.0 I tink