Visual Basic executable running in native mode, but not when starting from debugger

I have some big problems with my new environment and I think related to managed vs native code.

After my harddrive crashed I installed Visual Studio 2010 on a Windows 8 (which is new to me) and used backups of my Visual Basic .NET code files.

My issue is that the standalone debug executable crashes (with error code 0xc0000409) without me being able to see my source code ('No native symbols in symbol file'). It turns out it is running in native mode (Process: [140] myApp.exe: Native), which I did not think Visual Basic ever did.

When debugging from the GUI I have symbols and, to my surprise, it finds two MyApp.exe in the modules list, one native and one managed.

Some more details, I use ODBC, build for x86, and use .NET 4 client profile. As my project settings are similar or identical with my pre-crash setup I think the configuration problem is in my environment/OS, but I cannot find it after days of searching.

Can I make my standalone executable file execute in managed mode so I can debug it with symbols when it crashes? I have been able to do this for years with my old setup.

Any tips or hints would be very much appreciated.