This may be a timing issue.......

If put up a post then get a reply and log back into the thread is not showing the two posts until use Refresh from the browser menu.

[honeybee]

get the same problem but think have to delete temp internet files and hope problem will get away.

Make sure your cache setting are correct.
Netscape is, by default, very bad at refreshing itself
IE normally does it "automatically"...which means what ever mood it's in at the time. Set then to check for new versions of a page every time. I'm using IE5 and I have no trouble seeing new posts.