you may need to re-install, i can't really help to much, I've never really had that problem, but a re-install should fix it, won't take to long especially I've you live in the US or somewhere plus its only like 10gb i believe, if you're still having problem even after re-install maybe its a glitch with the new update and there will be a patch out very soon if thats the case i would suggest looking on steam forums or cs go forums to see if anyone else is having you're problem