Hmm..Try this one.
 Code:
$nul = SetOption("NoVarsInStrings", "On")
$nul = SetOption("NoMacrosInStrings", "On")

$network = @lserver + "\netlogon\programs\client.bat"

if @error<>0
   'Map Error was server: ' + $network + ' ' + @ERROR + ' - ' + @SERROR ?
endif

$runaspath = @lserver + "\netlogon\runnas.exe"

if @error<>0
   'Map Error was runaspath: ' + $runaspath + ' ' + @ERROR + ' - ' + @SERROR ?
endif

$cmd = '"' + $runaspath + '" user:domain\helpdesk "' + $network + '" /pass:password'
Shell $cmd

if @error<>0
   'Map Error was execute: ' + @ERROR + ' - ' + @SERROR ?
endif