Pdf Files in Outlook Express not opening -all others ok

Using XP & Adobe Reader 8.0

In Outlook Express 6.0 when trying to open a pdf file attachment keep getting the old “this file does not have a program associated” message.

Pdf files open fine if saved to a folder or desktop but not from within OE.

File association in Explorer set to always use Adobe Reader 8.0 but don’t work with the OE attachments within OE.

Also can’t find the folder within Documents and Settings etc where these attachments are held -are they hidden? Explore set to show hidden files.