I'm the person with the same problem he spoke of. We have similar rigs, except different graphics cards (I have nvidia, he uses AMD) and he's on Windows 10 while I am on 7. There seem to be no other correlation between us other then the fact that we stopped playing earlier today, and when we came back, we were both getting this error. I have also tried all the things he spoke off, and I have searched for the solution to this problem for about 2 hours now.

My only question is, is valve pushing server side updates? Like, updates that would not require a physical update to be downloaded, but one that updates the game internally (values getting changed for example)

Any help in this matter would be vastly appreciated.