Sys Restore entries but no restore

I've read relevant technet help. Plenty of space. Services are running. etc.

Calendar has entire month of June bolded dates. List only shows most current
restore point. Can't open on any other date. Event viewer logs an *sr* entry
referencing my scheduled NAV scan ending at 2:31am. Seems as though Norton
Anti Virus scan is causing problems with restore points being inaccessible.

Symantec site of little help. I'm aware of issues regarding rollback and the
effect that might have re lost Symantec updates. But it seems like I should
be able to do the rollback. Which is misbehaving, XP or Symantec? I've
disabled the UNessential daily virus scan, but it seems like I shouldn't be
having these problems. Any help or pointers appreciated. ed...