Got it! The $verb is a vartype=9, so the invokeverb command doesn't know what to do with an object. Therefore, try...

code:
$objShell = CreateObject("Shell.Application")
$objFolderItem = $objShell.NameSpace("C:\Documents and Settings\ShiltCK\Desktop\carbgramcounter.pdf").Self
$Verbs = $objFolderItem.Verbs
For Each $Verb in $Verbs
	if instr($verb,readvalue("HKEY_CLASSES_ROOT\lnkfile",""))
		$objFolderItem.invokeverb($verb.name)
	endif
Next

get $x