This problem was originally reported by Christian Ridderstrom.
Unfortunately, he cannot share his file here (You can contact him for a copy).

I've confirmed the problem with my installation.
The crash occurs when dia_font_set_height() is called with height 0.

Here is some backtrace information:

LIBDIA! dia_font_set_height + 23 bytes
LIBDIA! dia_font_build_layout + 42 bytes
LIBDIA! dia_font_get_sizes + 65 bytes
LIBDIA! text_line_get_alignment_adjustment + 525 bytes
LIBDIA! text_line_get_alignment_adjustment + 13 bytes
LIBDIA! dia_gdk_renderer_set_dashes + 2070 bytes
UML! umlclass_get_properties + 93839 bytes
UML! umlclass_get_properties + 93567 bytes
LIBDIA! dia_gdk_renderer_set_dashes + 4306 bytes
DIA-APP! 10014bd4()
LIBDIA! layer_render + 260 bytes
LIBDIA! data_render + 134 bytes
DIA-APP! 10014b1f()
DIA-APP! 10014918()
LIBGLIB-2.0-0! 0036a0a6()
LIBGLIB-2.0-0! 00368197()
LIBGLIB-2.0-0! 00368c90()
LIBGLIB-2.0-0! 00368f37()
LIBGLIB-2.0-0! 003693da()
LIBGTK-WIN32-2.0-0! 004ea91a()
DIA! 0040102f()
DIA! 00401135()
KERNEL32! 7c816fd7()


_dia_font_set_height:
00A712C0   push        ebp
00A712C1   mov         ebp,esp
00A712C3   mov         eax,dword ptr [ebp+10h]
00A712C6   push        eax
00A712C7   mov         ecx,dword ptr [ebp+0Ch]
00A712CA   push        ecx
00A712CB   call        _dia_font_new_from_style+306h (00a71064)
00A712D0   add         esp,8
00A712D3   push        eax
00A712D4   mov         edx,dword ptr [ebp+8]
00A712D7   mov         eax,dword ptr [edx+0Ch]
00A712DA   push        eax
00A712DB   call        pango_font_description_set_size (00a9c0ba)
00A712E0   add         esp,8
00A712E3   pop         ebp
00A712E4   ret
_dia_font_get_psfontname:
00A712E5   push        ebp