I have a TinyMCE editor on a page with the paste-from-word button enabled.
When I click the paste-from-word button a dialog shows up and let me paste the word content into a textbox. This works fine on Chrome and FF. On IE8 the dialog shows up, but the textarea seems to be disabled. I can't place the cursor inside or paste anything in there.
It's because you're using an old version of TinyMCE... Older versions of TinyMCE have issues with IE8 (and vice-versa). Update to the latest version of TinyMCE and you won't have this problem.