Hi Siddhu
Something we see sometimes with EG with a dialogue is that it opens on a different, non-existent, screen. Happens when you've had more than one screen in the past and now fewer. It might be this that is happening. Try the following when you try to join tables and EG appears to be hung:
Press ALT-Space, M, followed by one of the cursor keys.
Now move your mouse, and you may well find that the Tables and Joins dialogue pops onto your mouse pointer. You can then simply left-click to position the dialogue where your mouse pointer is.
Hope this helps