If you use IE, don't hit the refresh button at the top or F5.

You need to make sure the cursor is in the area of the thread (not at the top where the tabs are). Right click for the context menu, and select refresh. That will cause only the frame where the thread is to refresh.

For a more permanent solution, go to your temporary internet files settings and change the cache setting to "Every Visit to the Page". It'll clear things up peromanently.