>This is something new. I don't know if this is something specific to my IE 8 (although I have not changed any settings).
>But now when I am in UT and click on a message in the pane Last 10 messages, UT opens this message in a new UT window.
>Also, when I click on New button (as I am doing right now) the new message appears in a new UT window.
>Is this by design change?

If you got such behavior, it's time to re-login. It is not a normal behavior, but I sometimes get the same problem.