The system restore alarms are generally not false positives. They mean that historically, your computer hit the worm (doesn’t really mean the computer was ever infected, it can e.g. mean that you have received an email with an attachment infected by this worm).

The reason the System Restore files are hard to access is that by default, Windows sets quite strict access rights to the folder. Namely, even the Administrator cannot read the data in the folder. This may sound strange but that’s the fact. The reason avast on-access scanner can access the folder is that it uses low-level APIs and system process context for file access.

What you can also do is right click the System Volume Information folder in Explorer, and edit its ACL (Access Control List) - ie. the thing on the Security tab. Simply grant access to the folder to your account. You will then be able to see the contents of the folder (and so the avast on-demand scanner will).

Hope this clears it a bit,
Vlk