The problem is that the .net 4.0 framework build number has changed. This is only an issue during the beta, it doesn’t change once released. To work around this, open the DotNetConfig.xml in the FinalBuilder installation folder and edit the entry for .net 4.0 to look like this :
Sorry for the delay, I haven’t been able to reproduce the problem you’re having, could you send in the output from the action when using, and when not using the ‘Use MSBuild’ option.
The support for Visual Studio 2010 in FinalBuilder is based on the pre-release versions of Visual Studio 2010 which means the action may or may not be 100% compatible with 2010 when it’s released but we’ll strive to get an update out ASAP if it’s not.