Hi,
The VERIFYING ARJ-SECURITY ENVELOPE statement is normal. It is verifying that your file is intact and not corrupt. If this message goes away after a while without expandind, you have of 2 possible problems. 1. The file is corrupt and you need to download it again, 2. You need to extract it to the root of the volume or C:\drive if it's a PC.
Also, the bigger the patch the longer it will take to extract the file. For instance, I have to wait as much as 20-30 minutes at that prompt before it extracted for a major OS Service Pack.
Lou