emails that won't open

Hi, I'm new to this forum and still learning the basics of computer use. My problem is this: When I receive emails that have a black&white icon on the subject or attach line, the p.c. won't open it. When I try to open it, it is sent to my "u-lead photo explorer" where a blank screen appears and then that annoying "send/don't send" message appears, and no matter which choice is checked, it sends it back to "Outlook Express" without opening it. Any mail that either has no icon or has a colored icon on the attach line will open readily. If an email is blocked by "Norton" it usually states that a virus was detected. This has been going on since day one if I remember correctly. There are one or two correspondents whose mail, I've never been able to open because of this situation. And recently, at least once a day, when I try to open "outlook Express," there is a message that it can't be opened because of some connection not materializing. Rebooting cures that at least for the day. Please help. lol' Perry