When I try to launch Skyrim via Steam, it says

"Your game version is NOT supported, supported patches: 1.3.10.0us"

I am not in the Beta program, and I don't know why this is happening.

Help D:

Check your Game's Cache Integrity.

The 1.4 patch released about an hour ago. Wrappers like Skyboost and TESVAL are not compatible and may no longer be needed.

You also need to verify if any of your other mods are compatible with the new patch

http://www.gamesas.com/topic/1341190-patch-14-unofficial-topic-4-with-changelog/