You may very well have a problem with tcsh. Open the Terminal prefs and check to make sure you've selected "Use this shell", and that tcsh is the shell designated. Now open a new terminal window. Type 'ls -l /bin | grep sh'. If tcsh has zero size, and is owned by you rather than by root, tcsh has been destroyed. There are numerous threads on this issue, which most often manifests itself as new windows in Terminal dying with the message "[Process completed]". I recommend reinstalling if you do discover that tcsh has been zeroed. It won't harm anything, and the installer will only install over the things that need repair.
If this isn't the issue, there are a pair of things you can do. First, you can change the Terminal pref of "Use this shell" to /bin/tcsh. Second, if that doesn't solve it, you can open NetInfo and manually change your user's shell to /bin/tcsh. This second option should be approached with caution, as you can do severe damage to your system with NetInfo if you don't know your way around it.
Good luck.