A new error message has appeared on trying to open attachments C:\ WINDOWS\Temporary Internet File\Content.IE5\ - "Not a valid Win 32 application."
I would appreciate any advice please.
It sounds like you are trying to run an executable (a file ending in .exe) that is actually for an older version of Windows - Win 3.1.
On a different note, it may be worth checking any executable attachments with a virus scanner before trying to run them - there are lots of viruses around!