crash when calling show() in a module importing a swig generated wrapper module

I have a python module that imports a module generated with swig. When I try to call the show() function of matplotlib later in that module, python crashes. When I comment the imported swig module out, everything works fine. A backtrace obtained by debugging with gdb is shown below. Does anyone have a clue?

Thread [1] (Suspended: Signal 'SIGSEGV' received. Description: Segmentation fault.)
     27 __cxa_allocate_exception() 0xb74e324c
     26 py_to_agg_transformation_matrix() /local/vollmer/opt/matplotlib-0.99.1.1/src/agg_py_transforms.cpp:20 0xb4e11d88
     25 _path_module::update_path_extents() src/path.cpp:346 0xb4e19b3d
     24 Py::ExtensionModule<_path_module>::invoke_method_varargs() 0xb4e26451
     23 method_varargs_call_handler() /local/vollmer/opt/matplotlib-0.99.1.1/CXX/cxx_extensions.cxx:1403 0xb4e0d51c
     22 PyCFunction_Call() 0xb7ed5875
     21 PyEval_EvalFrameEx() 0xb7f28485
     20 PyEval_EvalCodeEx() 0xb7f2dd7f
     19 PyEval_EvalFrameEx() 0xb7f27574
     18 PyEval_EvalCodeEx() 0xb7f2db9b
     17 PyEval_EvalFrameEx() 0xb7f27574
     16 PyEval_EvalCodeEx() 0xb7f2dd7f
     15 PyEval_EvalFrameEx() 0xb7f27574
     14 PyEval_EvalCodeEx() 0xb7f2db9b
     13 <symbol is not available> 0xb7ec2c32
     12 PyObject_Call() 0xb7e9dc1c
     11 PyEval_EvalFrameEx() 0xb7f29242
     10 PyEval_EvalCodeEx() 0xb7f2db9b
     9 PyEval_EvalFrameEx() 0xb7f27574
     8 PyEval_EvalCodeEx() 0xb7f2dd7f
     7 PyEval_EvalCode() 0xb7f25c73
     6 <symbol is not available> 0xb7f47adc
     5 PyRun_FileExFlags() 0xb7f47b9b
     4 PyRun_SimpleFileExFlags() 0xb7f4858f
     3 PyRun_AnyFileExFlags() 0xb7f48818
     2 Py_Main() 0xb7f54e12
     1 main() 0x08048692