When I try to open Byte I get a message that says something like "The expression you entered contains a function that Byte cannot find". Byte won't open. What is going on?

There is a high probability that you have the Klez virus, or a close relative. You should do a thorough virus scan with a reputable antivirus software and get the virus removed - it is a particularly nasty one. Do not wait. Once the virus is removed from your system, simply reload Byte on top of the existing Byte installation. Usually your borrower files will be unaffected by the virus. You may need to reload other software as well.