Encrypting multiple pdf files

Dear all,

I am new in scripting with autoit. I would like to use autoit to encrypt .pdf files which are stored in a folder and then save them by "Enable Commenting & Measuring" option. I have the problem that sometimes during the execution Adobe Acrobat Reader is not correctly started and the script cannot be executed further. I use the following code to execute the Adobe Acrobat Reader. Do you have any suggestions to avoid such problems and ensure the correct execution of the script?

O.S.: Windows XP Professional X64
Adobe Reader: Acrobat reader X 10.0 Professional
Autoit: 3.3.8.0

#cs
Define Environment
#ce
;Debugingmodus wird aktiviert
AutoItSetOption("TrayIconDebug",1)
$acrobat = "C:\Program Files\\Adobe\Acrobat 10.0\Acrobat\Acrobat.exe"
$d = 500 ;Delay between commands
;Folder of the files
$filepath = $cmdLine[1]
;File name
$file = $cmdLine[2]

$fileopen = $filepath & "\" & $file
#cs
Start Acrobat Reader X with file
#ce
$title = $file & " - Adobe Acrobat Pro"
$handle = WinGetHandle("[CLASS:AcrobatSDIWindow]", "")
run($acrobat & " " & $fileopen)
WinWaitActive($title)
sleep(5000)

Thanks in advance!