Best Article --- check if the Dynamics AX 4 client crashes upon startup

This is a very common error we used to get while working with DAx and found below as a resolution for this..

If you get the following error when starting up a Dynamics AX 4 client and just can't see anything wrong with the configuration or anything else; look into the following folder on your local machine "\Documents and Settings\\Local Settings\Application Data\" for a file named "ax__.auc" and rename it or delete it.