While working on a little backup script I try to change the ACL of a file using Set-Acl in Powershell 1 on Vista and always get the following error message:

Set-Acl : The security identifier is not allowed to be the owner of this object.

This error persists even if I go a minimal script:

$acl = Get-Acl $sourcepath$file
$acl |format-list
Set-Acl -path $sourcepath$file -AclObject $acl

Does anyone know the reason for this error? Obviously I'm not changing the ownership of the file...

BTW: What I ultimately want to achieve is to reduce all access rights to ReadAndExecute. Is there maybe an easier way of doing this in Powershell?

Thanks for your help! Ulrich