Pat,

You can't start a service that is in the Disabled mode so you need to first set the Startup mode to AUTOMATIC, then actually Start the service. However, in your case if they have removed the files or enough of the files to prevent the service from starting then you need to at least set it to Automatic, then push out the Altiris Agent again.

Personally I like using the fnWMIService UDF from Chris S.
fnWMIService - Use the Win32_Service class of WMI to control services

NOTE! Chris has not updated the code yet though to support the NoVarsInStrings option. I have updated and posted an example here though for you to try.

Break On
Dim $SO
$SO=SetOption('Explicit','On')
$SO=SetOption('NoVarsInStrings','On')
 

Dim $SetService, $Remote
$Remote = 'computername' ; Name of the remote computer to start service on 
$SetService=fnWMIService('Altiris Agent','ChangeStartMode(Automatic)',$Remote)
? 'Change startmode error: ' + @ERROR
$SetService=fnWMIService('Altiris Agent','StartService',$Remote)
? 'Starting service error: ' + @ERROR
 

Function fnWMIService($sService,$sMethod,Optional $sComputer)
 Dim $objWMI,$objSrvc,$nul
 If Not $sComputer $sComputer="" EndIf
  $objWMI = GetObject("winmgmts:{impersonationLevel=impersonate}!\\"+$sComputer+"\root\cimv2")
  If @ERROR<0 Exit Val("&"+Right(DecToHex(@ERROR),4)) EndIf
  $objSrvc = $objWMI.ExecQuery('Select * from Win32_Service WHERE Name = "'+$sService+'"')
  For Each $objSrvc In $objSrvc
    $nul=Execute("$"+"fnWMIService = $"+"objSrvc."+$sMethod)
  Next
EndFunction