Having the same crash to desktop problem...I was able to play FF a few hours ago, but can't now.
I've deleted the sounds, the clientreg file, and ran SDK Base...nothing...
Also tried disabling the steam community...I see the loading screen for a long time, then hl2.exe just crashes to the desktop.
Windows Vista 32bit
Tried running in XP mode w/ admin, nothing.
*FIXED*
EDIT - Well I just ran the installer again (without uninstalling) and saw some files blow back into the folders...looks to be working fine now.