NTDOC you've come through again. Why do you think my code didn't work? I added the error line which didn't report anything and I run the code through a debugger which didn't report anything.
I ended up adding a goto statement if there already is a mapir.old file. I'm not sure how to have it check the version. I'll look through the manual to see if it tells how to do that.

Code:
 Dim $Source
$Source = ExpandEnvironmentVars(ReadValue('HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion','ProgramFilesPath'))
If Exist($Source +'\Common Files\System\MSMAPI\1033\MAPIR.OLD')
GOTO "reg"
Else
If Exist($Source +'\Common Files\System\MSMAPI\1033\MAPIR.DLL')
  Move  $Source +'\Common Files\System\MSMAPI\1033\MAPIR.DLL' $Source +'\Common Files\System\MSMAPI\1033\MAPIR.OLD'
  Copy '\\mnc17p1s\NETLOGON\batch\mapirnew.dll' $Source +'\Common Files\System\MSMAPI\1033\MAPIR.DLL'
EndIf


SWK, nope not Hungarian. I'm an American mutt. The name is either Dutch or German and we're not sure if it's shortened or not. Some controversy lingers. Thank you for all your help. The positive words encourage me to learn more.

John