I really doubt it is your Skyrim installation. Of course, this is just a hunch. But the game itself runs well on many many people's PCs. So it must be some weird combination of hardware, drivers or settings of those.
You are using a gtx590, which, I believe, is a very rare videocard. Nvidia didn't make that many of them, because of heat problems many users were experiencing. And the cost. The gtx590 was just an attempt to claim the "highest performance on one videocard" trophy. Have you tried to disable SLI ? If that is possible even on a gtx590. You wrote you are using the latest nVidia drivers ? (version 301.10). But do you also have the latest drivers for your motherboard ? (Chipset drivers for your motherboard include PCIE drivers. If they are faulty, that can have an impact on your gtx590, which has an interal PCI-E bridge. Which I think is a rare device).
Trying to think what else it could be. I have no clue, sorry.
Did you ask official Bethesda support ? (This forum is not the official way to get support. No Bethesda people ever post here).
Like you I too am at wits end. I have tried everything. Yes all the drivers on the system are current. I doubt it is the machine because there is no other title I have that has any single problem, especially like this.
I just deleted the entire installation then re-installed. Without doing anything else I ran the game. At the first save it was ok but once I got out of the cave headed to Riverwood the save issue popped up. Additionally I also checked the other issue of no sound for bow and arrow shots... nothing! I have sound for everything else. I manually tested all of the sound channels and they are all functional. The only thing I can think of with this would be that my system is a full 7.1 surround... and I wonder if Skyrim even supports it. Additionally I tried finding any kind of manual settings for sound but was only able to find volume control and nothing else. So there is no way to see what the channels are set to, what drivers are being used .. basically nothing for sound setting that I could find.
So I have no idea what the heck is going on here. Finally the reason it has to be Skyrim is because I installed it just now on a second machine that has a ATI card and main board sound, again 7.1 surround. And I get the same results! I tried to install without STEAM but apparently it is required. The only thing different is that my steam install and where I install any game titles is on another external drive. I do not have either STEAM or any games installed on the main C: drive on any system.
Perhaps that is the issue, at least with the save games loading?!
But then again, this save game issue was reported by many, many more people in the past.. for many the later patches must have helped but for me it seems they did not. I am not sure what else to try but I am going to try Bethesda's tech support. If they have no clue then I am just going to say the heck with it because it is too frustrating trying to trouble shoot a game that has issues and very little direct public customer backing and support. So either later today I will have some other options or Skyrim will get thrown in box to gather dust. And if that happens, I guess I will just have to stick with Oblivion, Ultima Online and Two Worlds for my D&D/RPG type gaming.