I actually got this too, recently while playing on a server.
It has NEVER happened me before. I smell hax. Or is this similar to the Memory Access Violation prompt back in the old cs2d days? probably, I am not sure though.
however it's a general error in most cases. can be caused by everything. either bugs in the cs2d code which occur very infrequently and therefore have not been found yet or maybe bugged situations caused by high latencies or even hacks.
therefore I can't provide a solid solution for you, sorry.