Invalid access to memory - System::UnicodeString::LastDelimiter1

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WinSCP 6.3.7

Error message:
Invalid access to memory.

Stack trace:
(002A7F0E) System::UStrAsg
(000990CF) ntdll.dll
(000783C1) ntdll.dll.KiUserExceptionDispatcher
(001219A5) System::UnicodeString::LastDelimiter1
(00B813D7) UnixExtractFileName
(00AEF080) TCustomUnixDriveView::NodeColor
(0049188F) Customdriveview::TCustomDriveView::InternalOnDrawItem
(004401A8) Vcl::Comctrls::TCustomTreeView::CustomDrawItem
(00492719) Customdriveview::TCustomDriveView::CustomDrawItem
(0043EC0F) Vcl::Comctrls::TCustomTreeView::CNNotify
(00492845) Customdriveview::TCustomDriveView::CNNotify
(00409031) Vcl::Controls::TWinControl::WndProc
(0043F39E) Vcl::Comctrls::TCustomTreeView::WndProc
(00409197) Vcl::Controls::_17076
(00409031) Vcl::Controls::TWinControl::WndProc
(00408678) Vcl::Controls::TWinControl::MainWndProc
(00226F7C) System::Classes::_18201
(0003298D) USER32.dll
(00023371) USER32.dll
(00022DEB) USER32.dll
(0002CF6D) USER32.dll
(0007837B) ntdll.dll.KiUserCallbackDispatcher
(00039BBD) USER32.dll
(00021DA1) USER32.dll.SendMessageW
(00099EF6) COMCTL32.DLL
(00051A14) COMCTL32.DLL
(000518ED) COMCTL32.DLL
(0004E20B) COMCTL32.DLL
(00051F97) COMCTL32.DLL
(0003298D) USER32.dll
(00023371) USER32.dll
(00022C32) USER32.dll.CallWindowProcW
(00409142) Vcl::Controls::TWinControl::DefaultHandler
(00409031) Vcl::Controls::TWinControl::WndProc
(0043F39E) Vcl::Comctrls::TCustomTreeView::WndProc
(00226F7C) System::Classes::_18201
(0003298D) USER32.dll
(00023371) USER32.dll
(00022DEB) USER32.dll
(0002CF6D) USER32.dll
(0007837B) ntdll.dll.KiUserCallbackDispatcher
(00039BBD) USER32.dll
(00021DA1) USER32.dll.SendMessageW
(0043C7A6) Vcl::Comctrls::TTreeNodes::SetUpdateState
(004917A5) Customdriveview::TCustomDriveView::CreateWnd
(00408530) Vcl::Controls::TWinControl::UpdateControlState
(004082C7) Vcl::Controls::TWinControl::CMRecreateWnd
(00492B0E) Customdriveview::TCustomDriveView::CMRecreateWnd
(00AEF7FE) TCustomUnixDriveView::Dispatch
(00409031) Vcl::Controls::TWinControl::WndProc
(0043F39E) Vcl::Comctrls::TCustomTreeView::WndProc
(00408282) Vcl::Controls::TWinControl::RecreateWnd
(00409031) Vcl::Controls::TWinControl::WndProc

The problem happens rarely. I cannot reproduce it.