All downloads on new comp corrupted?

[BobFungus]

Every single file I have downloaded for my new computer has been corrupt. I've used a second computer with a network connection that actually works to compare MD5 keys and the same files have different keys. I have NVIDIA Firewall, Microsoft firewall, Avast, and Ad-aware running on my computer. I have disabled all of these and yet the MD5 keys are still different and the files still corrupt. Can someone please help?