Mail is downloaded from O2 into Outlook Express, any identified spam is left in the spam folder on webmail.
But let me explain, the attachments that I can't open are historic and have previously been opened (using previous version IE and CA's eTrust AV).
This is why I'm certain that IE8 and/or Avira are causing the problem but I can't understand why all other file extensions will open except jpeg's.
I have checked that Windows Picture & Fax Viewer is functioning by opening photographs.
If Avira was blocking jpegs by reason of a setting then I would expect a message to be displayed such as when a web site is identified :
26/03/2009,15:14:53 [WARNING] Suspicious file: Contains HEUR/HTML.Malware suspicious code!
but looking at the avguard.log there is no record relating to jpeg files.
one more place to look in Outlook Express......Tools> Options>Security and clear the check box for Block images and other external content in HTML e-mail.
This was checked but is now unchecked but has made no difference, although I thought that this blocked incoming images in the body of the email.