It happens with both IE 6 and 7.
It's an IE MsgBox.
It's like IE doesn't understand the header with the "filename" command.
When IE asks me to "Open" or "Save" the file (recognizing the Content-Disposition header, I think) the name it shows is "Attachment.php?item=5" (where Firefox shows the correct filename "Prova Allegati.txt"). Then, if I choose to open the file (it's a txt file), IE shows the text, but if I try to save it I got the error.
The connection is SSL secured.
The firewall is not a constant in this problem: it happens to me and to other friends of mine in different cities with different networks and different PCs...
With Firefox installed on Ubunto or WinXP, I see immediately that there are no problems: the filename showed is the correct one.
Anyway, the problem IMHHHO seems to be right in the filename header... IE never shows the correct one.
Thanx for reply and... sorry for my poor English. ^_^