1. Disable or uninstall all Norton Add-ons.

2. Disable NAV's Email Protection: It provides no additional protection and
even Symantec says it's not necessary:

paste
Disabling Email Scanning does not leave you unprotected against viruses that
are distributed as email attachments. Norton AntiVirus Auto-Protect scans
incoming files as they are saved to your hard drive, including email and
email attachments. Email Scanning is just another layer on top of this. To
make sure that Auto-Protect is providing the maximum protection, keep
Auto-Protect enabled and run LiveUpdate regularly to ensure that you have
the most recent virus definitions.
/paste
http://service1.symantec.com/SUPPORT...02111812533106

3. Now try to open an attachment to a *new* message (i.e., one that wasn't
downloaded before disabling Email Scanning) and see if the problem persists.
--
~Robear Dyer (PA Bear)
MS MVP-Windows (IE, OE, Security, Shell/User)
AumHa VSOP & Admin; DTS-L.org

f5 wrote:
Recently attachments, other than jpg will not open. They always have
opened
before so I suspect the culprit to be new download/or update of a
Microsoft
product or Norton Internet Security. I can open jpg attachments. Other
attachments, when I try to open, the "mail attachment" box appears, and
when
I click on "open" nothing happens. I can however, save the attachment to
My
Documents and it will then open. but it will not open when I am in OE.
The
box is unchecked in OE that says not to open any harmful attachment.
Thanks
for your help.