Can't open Market application after updating my Samsung Galaxy Tab Just updated firmware for my Samsung Galaxy Tablet. 

Now I can't enter Market application. When I click the Market application icon, I get this message "Application not installed". And update was completed successfully with Kies.
Are you trying to access the Market from a home screen shortcut or from the app drawer? Updates can sometimes break shortcuts so try to open it from the app drawer. Another thing you can try is to reset market data from Settings -> Applications -> Manage applications -> All -> Market -> Clear data and Clear cache.