Its come to my attention that several people are having problems with their steam updating.
Heres how to fix:
Go into you steam/ valve folder and delete the clientregistre.blob
Make sure steam isnt running when you do this. Then start up steam
NOW WAIT. Go away for half an hour or an hour. It may tak a while to update, but once it does it just sits there doing nothing and takes about 15 mins to boot. You'll need to reenter your user name and password. Now wait some more. Should work!
Allow for maybe 2 hours to fix so do it ASAP