Disable the Office Plugin that comes with Symantec/Norton AntiVirus. See http://support.microsoft.com/?kbid=329820 "How to use Office programs
with the Norton AntiVirus Office plug-in" for more info.
It could be several reasons for this. The files may be saved in a folder
that you do not have permissions to. If this is the case, try saving the
files to another folder. Files may have been deleted.