I am trying to publish a new front end from my database. I have done this many times without a problem, but now all of a sudden I am getting a "Microsoft Access was unable to create an MDE file" error. Any ideas?

Typically you'll get that when the code won't compile. Go into the VBA editor and make sure the code compiles. Keep in mind that if it finds a problem and you fix it, you have to compile again, because it stops at the first error it finds.