Zipped files constantly "corrupt"

This has gotten extremely bad over the past few days. I have no idea what is causing it, or why. I've tried multiple browsers, downloading from different PC's (including my cell phone), and it still tells me the file is corrupt on my main PC.

First example: Downloaded NVIDIA WHQL and beta drivers. Both gave me 7zip errors when regularly running the install. Tried manually extracting with WinRAR. Gives me a file corrupt error. Tried installing 7zip and using that. Also saying files are corrupt. Had to extract on my laptop, then move the files over to my main PC to install the drivers.

Second example: Tried installing BF2 last night to play PR with some friends. Got to the part where I needed to patch to 1.41. Kept getting patching failed errors almost any time it was dealing with a .zip.

Third example: Tried installing the new NVIDIA PLA benchmark. Being told the .bin inside the .zip is corrupt.

Fourth example: Tried installing latest GTA IV patch. Being told the .cab (zipped archive) is corrupt.

Fifth example: Tried patching World in Conflict (downloaded it automatically in-game, and ran a setup file. Gets through, but at the very end, tells me a .cab is mismatching (aka "corrupt") and the patching fails.

I just tried reinstalling a newer version WinRAR and it gives me a CRC error during install. When I reinstalled an older version I had previously downloaded, it installed fine.

This is quite strange... I don't see how some zipped files can be "corrupt", and others aren't. I also don't see how an older download works, but a newer one wouldn't? Even if I download it from a different PC and bring it over, it says it's corrupt. But if I open that download on the other PC, it works just fine. I just ran 2 passes with Memtest86 and got zero errors. I'll run more while I'm at work tonight.

Any ideas? My C: drive is a 120GB Corsair Force GT SSD and my HDD (where most of these files are going, but not all) is a 1TB WD CB. The install of Windows is only a few months old. I've tried disabling anti-virus, and that hasn't helped.

 

Doesn't seem to let me edit my post again...

Used ALZip and was able to extract the PLA Benchmark, however it gave me a CRC error. I then started the install process where I was met with errors for every single file it tried to pull from the .bin to install.

Sounds like I may have a problem with my computer checking file integrity?

 

There is always a chance that downloaded files are corrupt; do you ever get corrupted EXE files from downloads (e.g. saying 'not a valid win32 file')?