New
#11
This happened to me, I had installed STEAM and CS:S shut down as normal, gone to bed, got up booted up my PC while I made a brew, when I returned my PC had started a recovery as apparently it didn't shut down correctly, when I got back to desktop STEAM.exe was gone along with other parts, but in C:/Programme files there was evidense of STEAM being there.
So I'm guessing this happened to you!
Odd, just make sure you create and delete restore points regular.
Also remember is only a beta type build so things go wrong!