Have you tried opening your preferences, and opening in a different shell? Also... Go to Apple's support forums at their site, and do a search on the subject there first, before you post. This has probably already happened to someone.
It sounds like you edited your.. well I'm not going to get into it.
I had a similar problem before, too. I tried to remote telnet into the Mac to check the processes and kill the offending PID with no luck. In the end, I had to reinstall OS X. I believe that some 3rd party software corrupted something...
Comments
It sounds like you edited your.. well I'm not going to get into it.
Apparently it's still related to the Apple Installer !
The two programs I installed before having this behavior are : JellyfiSSH & MPlayerOSXgui...
Don't know which one scrambled my terminal and i don't want to take my time to test.