OS 10.5 - Terminal auto executes program

Howdy,

Recently I wanted to add a filepath to $PATH or program to a directory already pointed to by the $PATH var. However, I guess I have been a bit too enthusiastic because everytime I start up a Terminal this program is executed and then followed by:

[Process completed]

After this I can't enter any commands. I can still enter commands through the Terminal menu: Shell -> New Command.

Can someone tell how to get this situation reversed?

Maarten