All my files I download are corrupted. New Mobo Asus M2A-VM?

Everything I download from the internet comes out corrupted. .exe file download full but when installing I get errors. When I download zip or rar files, it downloads full but when extract it says it is corrupted. I really need help and am really frustrated. I think it has something to do with my Mobo Asus M2A-VM but am not sure. Got all drivers and everything installed and know it is not network problems because I got other computers and they work on them. Please help thanks.