With a user-sent test file, I can reproduce a crash under windows 1.5.0, but not under linux. The crash happens if I open the file, open Toc panel (with no item), click on an include inset, and load the child document.
The error dialog says: Debug assertion failed! ....\path\to\VC\include\vector line 238 Expression: vector iterators incompatible The crash seems to happen at yx::frontend::TocModel::modelIndex() , with the following backtrace. Does this remind anybody of anything? Bo msvcp80d.dll!104f9961() [Frames below may be incorrect and/or missing, no symbols loaded for msvcp80d.dll] lyx.exe!std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> >::_Compat() + 0x30 bytes lyx.exe!std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> >::operator<() + 0x13 bytes lyx.exe!std::less<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > >::operator()() + 0x13 bytes lyx.exe!std::_Debug_lt_pred<std::less<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > >,std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> >,std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > >() + 0x13 bytes lyx.exe!std::_Tree<std::_Tmap_traits<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> >,QModelIndex,std::less<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > >,std::allocator<std::pair<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > const ,QModelIndex> >,0> >::_Lbound() + 0x59 bytes lyx.exe!std::_Tree<std::_Tmap_traits<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> >,QModelIndex,std::less<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > >,std::allocator<std::pair<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > const ,QModelIndex> >,0> >::lower_bound() + 0x20 bytes lyx.exe!std::_Tree<std::_Tmap_traits<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> >,QModelIndex,std::less<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > >,std::allocator<std::pair<std::_Vector_const_iterator<lyx::TocItem,std::allocator<lyx::TocItem> > const ,QModelIndex> >,0> >::find() + 0x3f bytes > lyx.exe!lyx::frontend::TocModel::modelIndex() + 0x42 bytes lyx.exe!lyx::frontend::QToc::getCurrentIndex() + 0xcb bytes lyx.exe!lyx::frontend::TocWidget::update() + 0x7a bytes lyx.exe!lyx::frontend::DockView<lyx::frontend::QToc,lyx::frontend::TocWidget>::update() + 0x19 bytes lyx.exe!lyx::frontend::Dialog::checkStatus() + 0xdc bytes