If your VS2008 BizTalk developer machine looses its ability to open or create BizTalk Projects, the reason is probably that a registry key has been overwritten by an update or repair to Visual Studio. The resiltuion is to find the registry key and reset it to its correct value.
The registry key can be reset as follows:
For 32-bit versions of Visual Studio 2008, the registry key is:
HKEY_LOCAL_MACHINESOFTWAREMicrosoftVisualStudio9.0Projects{FAE04EC0-301F-11d3-BF4B-00C04F79EFBC}PossibleProjectExtensions
For 64-bit versions of Visual Studio 2008:
KEY_LOCAL_MACHINESOFTWAREWow6432NodeMicrosoftVisualStudio9.0Projects{FAE04EC0-301F-11d3-BF4B-00C04F79EFBC}PossibleProjectExtensions
Change the value from
csproj
to
csproj;btproj