I'm running Ubuntu 12.10 64 bit, and I've run into an interesting problem. I can't download anything through the Software Center or apt. Going through the Software Center, I get a "package is not available on this mirror" error. I've tried changing mirrors so many times, I've forgotten how many times I changed them. I then tried to install Xfce through apt and it gives me a size mismatch error. Any ideas on what could be the issue?