If, when you are trying to perform “just in time” debugging, that is, opting to debug an application after it has crashed, and you are not offered the appropriate debugger, it might be as simple as adjusting an option setting.
For example, if
New instance of Visual Studio 2005
does not appear in your Visual Studio Just-In-Time Debugger dialog’s list of Possible Debuggers, then
open Visual Studio 2005
select Tools | Options… | Debugging | Just-In-Time
and tick the Native and/or Managed boxes