I already tried asking in the Norton forum, and was told to ask here.
The three subkeys which are causing the problem are overlayexcluded, overlaypending, and overlayprotected. It looks like they are supposed to show the backup status of a file by placing a small icon over the lower-left of the file icon, but NAO doesn't have the backup feature, which is weird.
Is it safe to delete these keys?
So a random user, not a Symantec employee, on Norton's forum refers you to your ISP? Have you been in contact with Norton's support department?
Telus, like any ISP, has a limited scope of support. No ISP that I know of will even touch the registry, let alone support editing or removing keys. In general, randomly editing the registry is never a good idea. Even Mozy's KB article does not say to randomly remove keys, but to uninstall the software you suspect of being a problem.
Are you sure Norton won't malfunction when random keys are deleted? (If it does, you'll have to remove and reinstall - Telus won't support registry issues)
I'm using Windows 7 Home Premium SP1 64-bit.
When Norton AntiVirus is completely removed, the overly icons show up as expected.
There are 14 keys present in this part of the registry. Three from Norton, three from Mozy, three from Adobe, three from SkyDrive, and two unknowns.
The keys appear to be in alphabetical order. An MSDN article describes how another part of the registry handles priorities.
I'm not sure Norton won't malfunction if these keys are deleted. I wouldn't be deleting keys at random—just these three. They look to be part of the backup function, which is not included in NAO, so I'm not sure why they are there.
I haven't tried contacting Norton support. I tried the Telus help page, but it wasn't much help. I will see if I can contact Norton support.