Give us an example of the attachment name, are you sure these are from a
reliable sender and something you really want to open.

If they are then maybe you need something installed to open them.

Example picture.jpg or picture.gif would be pictures that your normal
viewer would be "Associated" with. picture.jpg.exe is most likely a
virus. spreadsheet.xls would need Microsoft Excel to open it and
spreadsheet.ods would expect Open Office. If you don't have Open Office
installed then, for example, you will not have much luck with the .ods file.

Some attachments won't open directly from WinMail.  Try saving them to disk
and then try opening them from there.

steve