Error saving bitmap image data

Whyteboard 0.41.1
Operating System: Windows NT 6.1 (build 7600)
Screen Resolution: 1366x768
Python Version: 2.6.4 (r264:75708, Oct 26 2009, 08:23:19) [MSC v.1500 32 bit (Intel)]
wxPython Version: 2.8.10.1 (msw-unicode)
wxPython Info: (__WXMSW__, wxMSW, unicode, wx-assertions-on, SWIG-1.3.29)
Python Encoding: Default=ascii File=mbcs
wxPython Encoding: utf-8
System Architecture: 32bit x86
Byte order: little
Frozen: windows_exe

 File \"whyteboard\\gui\\frame.pyo\", line 250, in on_save
 File \"whyteboard\\gui\\frame.pyo\", line 274, in on_save_as
 File \"whyteboard\\gui\\frame.pyo\", line 252, in on_save
 File \"whyteboard\\misc\\utility.pyo\", line 152, in save_file
 File \"whyteboard\\misc\\utility.pyo\", line 169, in write_save_file
 File \"whyteboard\\misc\\utility.pyo\", line 218, in save_bitmap_data
 File \"wx\\_core.pyo\", line 2960, in SaveFile
PyAssertionError: C++ assertion \"Ok()\" failed at ..\\..\\src\\common\\image.cpp(2085) in wxImage::SaveFile(): invalid image