I have black bars on my 24 inch screen

Try lowering the refresh rate of the monitor.

HERE'S THE SOLUTION TO THE ATI BLACK BARS PROBLEM

It took months for me to find this on the web, so I thought I would share it here...

1) Open Catalyst Control Center
2) Use the drop down box at the top to click on Desktops and Displays
3) At the very bottom where your monitors are displayed, click on the little black arrow and click "Configure". Note that if configure does not appear, you are clicking on the wrong black triangle (you must use the one in the very bottom section).
4) This will bring up properties for that display. Choose "Full Screen" or "Maintain aspect ratio", whatever your preference. If you are getting black bars on all sides, you are likely on "Centered".
5) IF THE OPTIONS ARE GREYED OUT, as they were when I first tried this, the workaround is to lower your display resolution before attempting the above. Once you have changed the setting, you can return your display resolution back to whatever you like and the setting will remain as your display changes (movies, games, etc).

This works for CCC 9.4 and above, in my experience.

Hope that helps!!