Don't know, this code worked fine for me. Killed KIX32.EXE v4.5 RC1 no problem when using WKIX32.EXE to launch it.

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

Dim $Kill
$Kill=EndProc('KIX32.EXE',@WKSTA)
? 'Killing of KIX32.EXE ' + @ERROR
? Get $Pause ?
 

Function EndProc($Proc, optional $Computer)
  Dim $Process,$RC
  IF Not $Computer $Computer='.' EndIf
  For each $Process In GetObject('winmgmts:{impersonationLevel=impersonate,(debug)}\\'
   +$COMPUTER+'\root\cimv2').ExecQuery('select * from Win32_Process where Name='+'"'+$PROC+'"')
   $RC=$Process.Terminate
  Next
EndFunction