Hi Jim,
This is a very strange error that should never happen under normal conditions. You (your Windows user) don't need administrative privileges. The updater application is always executed with administrative or "elevated" privileges through User Account Control (UAC), irrespective of your user's privileges. Possible causes of this problem include:
- You have UAC disabled or customized in some nonstandard way.
- Your user does not have write permission on the local temporary folder (c:\Users\<your-user-name>\AppData\Local\Temp). This would be very strange, but theoretically possible.
- Your antivirus/firewall software is interfering with PixInsight's update system. This is also strange, but we have seen this kind of problems in a few occasions.
I hope these hints can help you to find the cause of this problem.