Core FTP

I had tried reentering my username and password as well as dumping the old program and redownloading it. None of it works. I don't have the option of going to the ftp administrator because I'm using the free program. I guess my only option is to go elsewhere and buy a program.

I was on coreftp yesterday morning with no problems and closed it out as I always do. About an hour later, I could no longer connect. I haven't changed anything but it says "authenticity failed". I redownloaded the program and I'm still getting the same problem. Any ideas? I have windows X...