GC,
Although I'm not experiencing this it seems this is a problem a number of users are and as you'll see from this message:
http://community.norton.com/t5/Norton-Internet-Security-Norton/Error-quot-8506-422-quot-appears-on-m...
Norton are working to resolve it.
It's a holiday weekend but I'll post a note asking them if there's any update yet.
I wouldn't run Power Eraser any more since it can sometimes do more harm than good if you don't know when to say No!
Can you say how the two OK machines may differ from this one? Different Windows or ....
I can't make any informed suggestions but if you wanted to try the following it just might do the job if you feel comfortable trying:
Make sure you have a backup of your identity safe
Download and install Revo Uninstaller and run it in the Full Mode 4 that you get after it analyses the system. Make sure that you get the free version and not the free trial of the paid for Pro version -- it's the left column with the download button at the bottom.
NOTE that when you do this the first stage is to run the normal Norton Uninstaller module so when that black Norton screen tells you that you must restart the computer to finish the job you MUST click on Restart LATER or it will follow instructions and you don't come back to Revo Uninstaller to finish the job. So Restart Later and then the Revo Uninstaller will ask if you want to go on and so do so for each of the remaining steps.
When it displays a tree of registry item to remove, click on the Select All button and then on Delete on the same screen -- not on Next below.
Do this also for the full list of left over files.
THEN restart the computer.
After that I would run Windows System File Checker:
Here's a link to the Microsoft instructions on how to do this:
http://support.microsoft.com/kb/929833
After doing that and rebooting that should at least assure you that you have a clean Windows base and then I'd log onto your MyNortonAccount and use the Download button since this will download and install a preactivated copy of NIS that is nearly current but not the absolute latest (which might be a good thing <g>)
If you find that you are told you have used all available activations then contact Norton OnLine Support via CHAT as below and ask them to release an activation to cover this reinstall although if you have Norton Management activated I understand you can do this yourself.
To contact customer support Click on this link https://www.norton.com/chat and work on from there.
I can't give you any guarantee that this will fix it or make it any better but iit's what I would do while waiting for the Norton Team to find and cure the trigger.
If you've any queries ask first ...
Please let us know how you get on ....
Hugh
