It loads partially, but then says an update is available and goes to the steam store page.
It usually autoupdates, but that function appears not to work.
Anyone else having this problem?
Dudemon
Enough free space (1+GB) on the drive you have MPQ files stored (Steam directory, in most cases C: drive) ?
Run commandline with admin rights (google it)
and run:
chkdsk c: /f
confirm with Y (two times) and restart computer to check disk for errors.
Run antispyware tool
adwcleaner - http://www.bleepingcomputer.com/download/adwcleaner/
and later (especially if something found) MBAM free/trial version
https://downloads.malwarebytes.org/file/mbam_current/
install, run, uninstall