a few people i know have been having issues with not being able to install/run csgo after this recent update due to ERROR 55 , if you get this

1: goto the steam website and click INSTALL STEAM, this will download the msi file.
2: goto control panel then programs and features select STEAM and click REPAIR.

3: run CSGO and watch it update then launch.

Disabling Big Picture beta did it for me

how do u disable it?

nm found it.. opt of out beta then do a check for new client from the steam drop down menu and it finds one, restarts steam and works

My brother done this and it worked for him and me:

Opt out of steam beta.
Restart steam.
Check for steam client update.
Restart after update complete.
Launch CS:GO.