Since I was specifically asked to post my opinions on this matter (even though they've already been stated) I'm here...
It sounds like either your computer is caching data, or the forum is, I'd suggest first clearing your cookies on your pc then delete your temporary internet files.
IF that doesn't work, clear your forum cache.
If this doesn't work, delete the appropriate cached files from your cached folder; I wouldn't recommend removing *all* files from the cache, but considering I purge them for a beta test it shouldn't be too much of an issue.
And for note, it's not necessarily only files that you don't need in your cache, classic stored other files in the cache directory as well that one wouldn't have to routinely purge.
