It sounds like the .bash_rc or .profile files got screwy, which would cause this type of issue. You may have installed an app that messed with these or other files. You can check if these files are present by entering,
If they're there you can back them up (in case they contain something you need),
Code:
/bin/mv .bash_rc bash_rc
/bin/mv .profile profile
Then restart Terminal and see if it starts normally. If it does you'll know one of those files contains some bad syntax.