BleepingComputer.com: Vista email attachments

Hi. I am trying to help my sister with her new computer. She knows absolutely nothing and I know just a little bit more. Here is the problem. She has vista and gets her online connection through at& t. When she receives an email with an video attachment and she downloads or runs it, it goes through all the motions of opening. But in the end it says
"files system error" -1072884953. I have tried googling that error number but haven't had any success. the computer says the files involved are

C\users\sisters name\App Data\local\microsoft\windows\temporary
internet\files\low\content .IE5\MVCNSOSO\name of attachment\wmv.

She does have the windows media player on her computer. PLease help. I have googled everything I can think of and haven't come across anything even remotely like my problem.

We have tried to open at least 4 different kind of attachments but the same thing happens. Her PC is about a 2 month old and is a Dell.

What email program are you using?

Her internet connection is from U-Verse and her email is AT&T.

By email program, I mean Outlook Express, Outlook, Windows Mail, Thunderbird, Gmail, etc...

Sorry it takes me so long to reply and I thank you for taking the time to try and help me. Her email is AT & T powered by Yahoo. Her email address looks like hername@att.net I hope this is what you are asking. She doesn't have windows mail or hotmail or comcast mail or outlook or anything like that. It is just att powered by Yahoo. Yahoo is her home page. She used the email set up that the internet guy set her up with.

I wanted to add something we just realized: with one of the attachments (.wmv) we are able to save the attachment to the desktop and then view it there which I think is odd and I don't know if all of them will be like this but they will not open up as they should. I get the "files system error" with the code -1072884953 when I try to view them in my email program. Also, and I don't think this has anything to do with this problem. When I turn off the computer....right before it turns off the message "the exception unknown software (0x000005) occurred in the application at location 0x76aabe16".
The message flashes quickly, for a millisecond and I had to shut it off many times in order to get that info. I may be wrong concerning the zeros.