Does this happen with other browsers or versions of IE? What version of SEP are you running? What features of SEP are installed? have you tried disabling SEP and see if the attachments open?

We're seeing the same exact behavior today at the public library where I work, and 3 different patrons have brought it to my attention this morning. I don't use Yahoo normally, but since no one has complained about this before now I'm thinking it's something new. You click Download file, or click the file icon itself, either way it quickly scans and reports that scanning is complete and nothing was detected. You hit Continue, and then you're back at the beginning again -- the dialog to Save or Run the file doesn't appear as it normally would. You can do that all day and never get the file open -- except that one (out of maybe 100 tries) we DID get the dialog box to open the file. Just for testing purposes I continued to try to re-open that attachment in that mail on the same machine, and could never get it to happen again. Doesn't seem to matter what browser is being used (same result in both IE 8 and Firefox 7), what OS you're running (happens with XP and Windows 7), what type of attachment you're trying to open (tried it on .pdf files and .doc files on several machines that have Acrobat and Word installed) or what type of antivirus program is installed on the computer (same on ones using Norton 2011, Microsoft Security Essentials and an old version of Symantec Corp. Ed.) Also tried temporarily disabling Norton Antivirus 2011 Autoprotect on one of the machines; no change.  I've tried it on 6 different computers today with the same result. If I forward those messages to a different mail program (so far tried Gmail and Comcast) the attachments open normally.  Possibly a Yahoo issue? If so, I hope it gets fixed fast -- this is causing havoc arround here.

Ok -- temporarily turned off Javascript in Firefox to force Yahoo to offer me the option to use their older 'Classic' mail version. Once I accepted that offerI tried to open mail attachments. With Javascript still disabled I got the message: "The connection to the server was reset while the page was loading."  So I re-enabled Javascript, and then trying to open the mail spawned a new Firefox tab that said 'Connecting' for a couple of minutes, then finally DID give me the Save or Open dialog. But tried it again, and it won't do it now. 

The fact that other mail clients like Gmail work properly leads me to believe it is not SEP related. I tried replicating the issue with Yahoo Mail in my lab with IE7 and FF with no success.

Yahoo when POPped into another email client and checked seems to be immune to this issue. However if some one affected could tip off Yahoo Help Central regarding the issue the customer care would be in a position to liasion with Symantec and get the issue sorted out for everyone.

Not SEP issue,

In some cases yahoo does not open attachments because it has virus on the file. Try to Re-open again the mail. If norton does not find any threat, Then you can downlaod the attachment/s safely.

Hi Joan,

What type of file you are attaching.. Some times .exe files having some malicious activity and Yahoo mail uses norton AV to scan. It also could be a reson.