Steps to reproduce:
I just started the program and it crashed.

Stack trace:
I don't know if this is a stack trace - I followed the link but found no pitivi-dbg package - but I think this could be useful.

I tried running pitivi from a terminal and the error message was this:

peterson@marvin:~$ pitivi
The program 'pitivi' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadValue (integer parameter out of range for operation)'.
  (Details: serial 167 error_code 2 request_code 140 minor_code 19)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

So I did what it suggested and that's what I found:

peterson@marvin:~$ pitivi --sync
DMO dll supports VO Optimizations 0 1
DMO dll might use previous sample when requested
Total Unfree 60 bytes cnt 1 [(nil),0]
Traceback (most recent call last):

+ Trace 197736

Other information:
Few times I managed to open the app, but when I did I couldn't import anything, and then the program crashed again...