title: [ADSI]::Exists throws an exception instead of returning False
body: <p>I'm trying to create a user using the ADSI object if it doesn't already exist. Here are the strange results I'm getting</p>
  
  <pre><code>#Check a user that I know exists
  [ADSI]::Exists("WinNT://localhost/micah,user") #True
  
  #Check a group that I know exists
  [ADSI]::Exists("WinNT://localhost/administrators,group") #True
  
  #Check a group that DOESN'T exist
  [ADSI]::Exists("WinNT://localhost/whoops,group") #False
  
  #Check a user that DOESN'T exist (NOT specifying that the obect is a user)
  [ADSI]::Exists("WinNT://localhost/test") #False (This works fine)
  
  #Check a user that DOESN'T exist (specifying that the obect IS a user)
  [ADSI]::Exists("WinNT://localhost/test,user") 
  #Throws exception "The user name could not be found"
  </code></pre>
  
  <p>The last line makes no sense to me. Why would it throw an exception when I specify that I'm specifically looking for a user, but when I DONT specify that I want a user it works just fine? This seems completely unintuitive to me. What am I missing?</p>