Sometimes, especially after making changes to your configuration files, you may have problems with your environment. These are usually caused by errors introduced when the files were changed.
Typically, a ``dot file'' will stop running when it reaches the first error. Look at how much of your environment got configured and at the configuration files to figure out where the error is. If there is a problem with the .xsession file, there may be an error logged in .xsession-errors which will lead you to the problem.
If your window manager isn't working correctly, you might have trouble logging in normally to fix the bug. In that case, try logging in with gdm normally, but press F1 instead of Enter after typing your login name and after typing your password; this should start up X with a minimal working environment that will allow you to make corrections.
If your dot files have gotten very out-of-date, or are so messed up that you want to start over, the program /usr/local/bin/resetenv will move your old dot files to a temporary directory and give you new copies of the current default files used with new accounts. These files are also available for copying from the home directory of user template.
If you haven't changed anything and are having problems, it's possible something is wrong with the workstation or the network. In that case, please contact one of the system administrators.