通过Powershell运行时，MSBuild失败

I have an MSBuild script that I want to call from a PowerShell script as part of a deployment process. If I call the build script via a bat file all works well. If I do the exact same thing in PowerShell I get CS1668 error looking for wierd and wonderful paths that dont exist on my machine. I know I am getting into the MSBuild script as these errors are occuring from within the MSBuild script targets (logging output is showing this). The bat file and the PowerShell script reside in the same place, right next to the build script.I have an MSBuild script that I want to call fr