Since last night, every time I try to send an email to a particular address – which I have used many times before – I receive a delivery failure notice. When I try to read the notice, I get an error message saying that there is a problem with the message loading and then my computer crashes. No other emails are causing this problem and, as long as I don’t try to open those delivery failure messages, my computer seems to be working fine. I have the Avast home program and it does not indicate that it is detecting a virus.
Should I be concerned that my attempts to open the delivery failure notices have been infecting my computer with a virus? Or should I assume that there is just some sort of temporary problem with the recipient’s internet service provider that is not harmful to my computer and will eventually be fixed?
Welcome to the forums, junebug. 
What email program are you using?
First, try running a boot-time scan with avast to check for malware.
Right click the “a” ball in the tray > select Start avast! antivirus > when the user interface loads, right click near the top left of the interface > select Schedule boot-time scan > be sure Scan all local disks is marked > click Schedule button and follow directions.
Thanks CharleyO.
I have figured out that the problem is not with sending an email to the particular recipient to whom I was writing, but with the fact that I am trying to send photos. I have never had this problem with photos before, but I have tried both Yahoo! and Hotmail and I am suddenly unable to forward photos from either account. As I said previously, the really odd thing is that trying to open the “undeliverable” messages causes my computer to crash.
I tried the scan you suggested, but no viruses were detected and the problem still exists. Any other thoughts?