Sorry, I report again the same problem.
I've a test case that triggers the problem.
Debian GNU/linux with kernel 3.5.2
Librecad from git repository
I've built a drawing with librecad.
I've make a block from part of a draw and exported it as a file (attached).
When I open the related dxf, everything is fine.
If try to insert it (File -> Insert -> Block), librecad crashed.
Attached : the bt from gdb, valgrind summary, the dxf file