Winsock error?

Hi, I’ve recently been having a problem with my ftp program. Whenever I try to log on to my schools server, it gives me a Connection failed (10053: Software caused connection abort) error. Doing some research, I’ve found that this might have to do with a winsock error or something? I came across one website telling me to set my router’s MTU setting to 1500, but when I try this, I lose all connectivity. Does anybody know what’s wrong? Prior to this, I was using Verizon DSL, but now I have Verizon FIOS with a D-Link DI-524. I’m using Windows XP Pro SP1.