Why is my game constantly crashing silently to desktop with no error message?

Maybe your computer or graphics card is getting too hot. Check how long you can run Skyrim until it crashes.

Also, check this out -> FIX for CTDs and Missing Textures I heard it does a very good job of preventing CTDs.

And save often!

I had the same problem that you. I've an ASUS GTS450 for video card, and at some point after enter and reenter from cities and buildings, it's become to loose image mapping (for example, a texture is just a empty violet or yellow color). This is happens in any condition and/or video configuration, low or ultra.

After a research I think it's a memory leak, I think the garbage video doesn't work as expected so it's an acumulation of a lot of things (not bugs), just a sample overflow.

Working with 8GB and the following patch that converts the max use of 2GB to 4GB for memory game use, doesn't solve at all the problem but it's a refresh because right now, my game doesn't crash often, just one time every two days.

Patch: http://skyrim.nexusmods.com/downloads/file.php?id=3211