PS script works in console, but fails when called from cmd prompt

I have a script that quite simply sets ACLs on a few reg keys and a folder. Nothing too complicated at all. The script works perfectly when run from the console, but when called from a command prompt using the following command, it fails miserably:

powershell -command Get-Content "c:\temp\script.ps1" | powershell.exe -noprofile -

The script runs, but simple things fail, such as:

Get-Acl-Path"HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall"

This works from the console but when called from a command prompt, I get "Get-Acl : Cannot find path 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall' because it does not exist

I've tried changing it to HKEY_LOCAL_MACHINE\... to no avail as well.

Is there something in the way of syntax that works under the PS prompt that doesn't work when called under the normal command prompt?

I know, I could drag out SubInACL and such, but was kind of hoping to get this to work.

By the way, this is running as the SYSTEM account.

Thanks.