script cancels because of autoit error

the following script cancels because of a autoiterror. the built in error routine says that
the error line is -1 and the windescription is "no such interface supported"
please note this script runs all the time ok and only cancels sometimes. since the script cancels at line -1 i am only including the first part of the script and the error routine.

#include <IE.au3>
#include <Array.au3>
#Include <File.au3>
$WshNetwork = Objcreate("WScript.Network")
$cpuserid = $WshNetwork.UserName
hotkeyset("{f9}","terminate")
dim $lenusername, $username, $locblank, $lenlastname, $sSearchString, $sSearchString1
dim $regtype, $tsoind
dim $filect, $flertct, $personid, $userid,  $ruserid, $firstname, $lastname, $middleinitial
dim $typeofemp, $reqtype, $reqtype, $firstowner, $defaultgroup, $useridin, $rebootsw
dim $msg, $idx, $idpre, $btext, $returnvalue, $numids, $lastid
dim $holdids[10]
local $array1[4]
$array1[0] = "p"
$array1[1] = "q"
$array1[2] = "y"
$array1[3] = "z"
local $array2[7]
$array2[0] = "e"
$array2[1] = "f"
$array2[2] = "g"
$array2[3] = "h"
$array2[4] = "i"
$array2[5] = "n"
$array2[6] = "o"
local $array3[4]
$array3[0] = "c"
$array3[1] = "d"
$array3[2] = "r"
$array3[3] = "s"
local $array4[4]
$array4[0] = "t"
$array4[1] = "u"
$array4[2] = "w"
$array4[3] = "x"

$oMyError = ObjEvent("AutoIt.Error","MyErrFunc")  


Func MyErrFunc()
  Msgbox(0,"AutoItCOM Test","We intercepted a COM Error !")
  $errormsg1 = "error line " & $oMyError.scriptline & @lf
  $errormsg2 = "err.description is: "	& @TAB & $oMyError.description & @lf
  $errormsg3 = "err.windescription:"	 & @TAB & $oMyError.windescription & @LF
  $errormsg = $errormsg1 & $errormsg2 & $errormsg3
  msgbox(0,"",$errormsg)
  exit
 
;Endfunc