I started playing again about a week ago, and finished up the main questline. I wanted to visit all the dungeons, which led to to revisit Blackreach. I have been here before, so I still have the sphere, but no blank lexicon, as that was probably consumed during a quest. Anyhow, I cannot enter Blackreach. I have tried entering from two different ruins, and the Alftand Lift. I get booted to desktop during the load screen every time, but there are no error messages. I have deactivated any/all mods, and I am playing the original game with no DLC. I am on Steam. My specs are as follows:

Win8 Pro 64-bit with all current updates
Core 2 Quad Q6700 2.67 GHZ
4GB ram
Geforce GTX 560 2GB (non-Ti) with the 314.07 drivers (upgraded from 312.xx during this. Didn't help)
Crucial M4 SSD 64GB (2 actually. 1 boot drive, 1 that has steam on it)
Pretty reliable cable modem connection.
List of previously active mods:
* Scarlet's Mobile Fortress
* Instant Merchant
* The Abysmal Depths
* Breezehome Mines
* Caliente's Body Mod (CBBE Curvy Edition)
* Project Reality: Climates of Tamriel - Lite Version
* Dungeon Quest Awareness
* Unknown Cave - new huge dungeon
* Moonpath to Elsweyr
* High Res Texture Packs 1, 2, and 3
* Journey to the Center of Nern - The Beginning
* Mysterious Merchant
* Oddveig's Tomb
* Quest: And the Realms of Daedra
* More gold from Merchants
* Bladestorm - One Handed Version
* Wheeze Dungeon Pack #1

Any of these known to cause any issues? All mods came from either Steam or Skyrim Nexus. The Steam client was installed new, but the game folder was copied from a Win 7 64-bit data drive. I have not attempted to play off-line. Should I try to delete local content, and reinstall Skyrim (keeping my save games files hopefully)? Any suggestion would be appreciated. Thank you.