It has been well publicized that Visual Studio 2010 introduced the ability to debug dumps of managed processes in mixed mode (as opposed to the old days of native debugging + SOS in the Immediate Window). The one fact about this new feature that often gets overlooked or forgotten is that mixed mode debugging only works for dumps of processes that were running on CLR v4.0.
You might ask, “why only do the feature halfway?”. The answer to this, is that the ability to debug dumps of managed processes in mixed mode required an architectural change by the CLR team that was made in v4. So dumps of processes that were running .NET 3.5 and previous will still need to be debugged using SOS.
Can’t remember or not sure which version of the CLR the process was running on? The new Visual Studio 2010 Minidump Summary page tells you: