Update: Bethesda has offered a solution to game crashing caused by the recent PC Skyrim patch.
If you're having trouble running Skyrim after today's small Steam patch, please try the following:
1. Right click on the game in the Steam library and select Properties
2. Navigate to the "Local Files" tab
3. Click "Verify integrity of game cache"
Also note that verifying your game cache will reset your SkyrimPrefs.ini file. If you are manually editing settings in that file, create a backup prior to verifying the cache.
Original story: PC Skyrim has been patched, and the RAM-boosting, crash-preventing, third-party Large Address Aware (LAA) mode outlawed.
PC Skyrim, following the 18MB patch, now runs only through Steam. The LAA mode, which required some executable-file manipulation, no longer works.
The problem being that the LAA mode enabled PCs to use more than 2GB RAM, which not only helped stability, but boosted performance of the core game and the numerous mods applied on top.
The ball's in Bethesda's court.
The Digital Foundry Skyrim face-off assessed all three versions of Skyrim - PC, PS3, Xbox 360 - to find out which is best.