Thanks for your help, everybody. The problem was that I had changed mail to port 26 in /etc/services about 2 weeks ago. I did this in an attempt to be able to move the box to my house, as I am on cable internet. It ended up not working (for obvious reasons I didn't know before), but I didn't change back the file when I took the box to another friends house. I am not sure why it started acting up all of the sudden this week, as it has been well over two weeks, without any incident. Thanks for all of your help.