Game Crashes w no error msg on entering random maps

After crash the game will not load at all (still no error messages) unless I run the packcheck in the install files. Happens three or four times per six hour session. Often the game will act like there is a patch I am missing after running the packcheck. (that I do not see documentation of on the site)

things iv tried to fix it:
>clear cache
>decoupling from steam and re-install stand alone client
>re-install windows/driver check

64bit, win10, 16gigs ram, i7