Hi ddebby:
Firstly, please provide detail imformation about the error you get? Then I think this article may help you,
https://azure.microsoft.com/en-us/documentation/articles/azure-stack-run-powershell-script/ , below the article there is also a reply about ".\InstallAzureStackPOC stopped", and the solution may be of use to you.
Wish this can help you!