Email is possessed please help


New Email
I have accounts, two of them. I am using Windows Live Mail. Everything was working fine until this past Monday. My wifes work computer stopped started sending emails sporadically and then just stopped sending altogether. It receives fine and the sent messages go out of the outbox and show up in the sent box. No error message, they just dissappear. Logged on online and can send from there just fine. The other computers in my house would send from that account just fine. So, we just used my computer to go around the problem. Today, half way through the day my computer started doing the same thing. I am stumped please help. I have checked the settings and they are the same. Talked to the IT guys at embarq and their end is working fine. Changed from landline to wireless on wifes computer no fix. Deleted and reinstalled her account on her computer no fix. Please help I need this up and running as this is our business. Thank you in advance.