Some salient points first.

I had downloaded Skyrim some time ago and have platyed it on PC on and off.

I purchased the Anthology and installed Oblivion on my PC as well and played it while offshore off of the disk.

When I got home and had decent net I booted up Steam and entered my product code to download for the primary purpose of getting all of the extras on Oblivion.

After Oblivion, Morrowind and Skyrim updates were downloaded to my PC I tried booting up both Skyrim and Oblivion and have an ERROR CODE 80 when trying to boot them up.

Morrowind has the same issue.

I assumed Skyrim and Oblivion were conflicts due to earlier games but I have never had Morrowind before on my PC.

Any ideas on what I can do to get rid of the error and boot up my games?

Thanks.

Try shutting Steam down, removing ClientRegistry.blob, and then restarting Steam.

Yep what DS said. You need to delete the ClientRegistry.blob file and I had the same issue when I was installing Shogun 2 TW via disc, so deleting the .blob file fixed my issue back then and I'm pretty sure it will fix yours too.