Problem using iNotes Web Access on Domino using IIS

Using iNotes Web Access (template inote6.ntf in rel. 6.5) on a Domino 6.5 and Microsoft IIS as HTTP stack (SO Windows 2000 advanced server Service Pack 4), the Websphere Plug-in returns an error when trying to view an attachment in a sent and saved email message (only in a sent message!!).

The error is:

ERROR: ws_common: websphereExecute: Failed to read from a new stream; App Server may have gone down during read

The Domino server is not down and works fine. All other requests are carried out.

Any hint welcome