# Add in the .DEFAULT User Profile
$DefaultProfile = "" | Select-Object SID, UserHive
$DefaultProfile.SID = ".DEFAULT"
$DefaultProfile.Userhive = "C:\Users\Public\NTuser.dat"
$UserProfiles += $DefaultProfile
# Loop through each profile on the machine</p>
Foreach ($UserProfile in $UserProfiles) {
    # Load User ntuser.dat if it's not already loaded
    If (($ProfileWasLoaded = Test-Path Registry::HKEY_USERS\$($UserProfile.SID)) -eq $false) {
        Start-Process -FilePath "CMD.EXE" -ArgumentList "/C REG.EXE LOAD HKU\$($UserProfile.SID) $($UserProfile.UserHive)" -Wait -WindowStyle Hidden
    }
 # Manipulate the registry
    $key = "Registry::HKEY_USERS\$($UserProfile.SID)\Software\SomeArchaicSoftware\Configuration"
    New-Item -Path $key -Force | Out-Null
    New-ItemProperty -Path $key -Name "LoginURL" -Value "https://mednet.uclahealth.org/" -PropertyType STRING -Force | Out-Null
    New-ItemProperty -Path $key -Name "DisplayWelcome" -Value 0x00000001 -PropertyType DWORD -Force | Out-Null

    $key = "$key\UserInfo"
    New-Item -Path $key -Force | Out-Null
    New-ItemProperty -Path $key -Name "LoginName" -Value "$($ENV:USERDOMAIN)\$($ENV:USERNAME)" -PropertyType STRING -Force | Out-Null
# Unload NTuser.dat
If ($ProfileWasLoaded -eq $false) {
    [gc]::Collect()
    Start-Sleep 1
    Start-Process -FilePath "CMD.EXE" -ArgumentList "/C REG.EXE UNLOAD HKU\$($UserProfile.SID)" -Wait -WindowStyle Hidden| Out-Null
}