The team blog of the Expression Blend and Design
We thought it was worth calling out this item as it may be an issue some of you encounter.
If you are trying to test build a project (Project | Test Project) immediately after installing WinFX and Expression Interactive Designer, but Expression Interactive Designer was never launched before, your build attempt might fail with the following message: “Error MC1000: Unknown build error”. If this occurs, you will need to close Expression Interactive Designer and launch it again.
Quite painless, hopefully, but worth knowing.