If you are running WWF (Windows Workflow Foundation, part of WinFX) on a x64 box, and have problems debugging workflows, stop.
It's currently not supported. It should, but does not work yet. This should be fixed already, but it's not. And it will probably get fixed in the next CTP drop.
There is a workaround though:
- Enter Configuration Manager (Build/Configuration Manager)
- Select the active solution platform drop down, select New...
- Select x86 platform
- Hit OK and try debugging again
This will make sure that you are running your solution debugging under x86 mode and thus allow you to set breakpoints and debug your code.