Process completed immediately after opening Terminal After I open Terminal in OS X:

Last login: Tue Oct 28 10:29:21 on ttys000 login(14773,0x7fff7572f300) malloc: * error for
object 0x7fd4bb715110: pointer being freed was not allocated * set a breakpoint in
malloc_error_break to debug

[Process completed]


I have no idea what I did or how to fix it.
Go to Preferences → General and set Shells open with to Command, and enter the following:

/bin/bash -x


Open a new shell and see what is being run, then remove the relevant lines from your profile files.