Access violation and page fault on Close of MDI form

I have an application that has been under piecemeal development for a couple
of years in BCB 5.  The application has always been required to support MDI
children with a TRichedit component and has done so until this afternoon.

When I close the MDI child I am now seeing an error

EAccessViolation with message "Access Violation at address BFF7B997 in
module 'KERNEL32.DLL'.  Read of address 40030E6C."

and then BCB drops me onto line 940 of forms.hpp

 /* TCustomForm.Destroy */ inline __fastcall virtual ~TForm(void) { }

before declaring that the application has committed an illegal action and
will be shut down.  The error message details say it's committed a page
fault in kernel32.dll.

I've traced down both paths to the MDI shut down and found nothing more
obvious, but the operation dies on this line.

I had been working on a module using and then clearing STL vectors and maps,
and new'ed and delete'd objects they refer to, and switching the
SelAttributes font in the Richedit component.  I am not sure how I've
offended the forms.hpp but I guess I have.

Any advice or prior experience would be greatly appreciated.  Thanks in

Wally Hooper
American Indian Studies Research Institute
Indiana University