When i do mephruns (2-4 minutes each game), after 3-4 games i lost possibility to make or join the game. Diablo 2 show this message "game does not exist".

And for example:
create game : gamm23
"Game does not exist"
after that i try to make this game again
create game: gamm23
"A game already exists with that name"
join : gamm23
"Game does not exist"

I do games very fast or what is the problem?

p.s.:sorry for bad english.

Try relogging and trying again. If not, just wait a few minutes, it usually goes away. Worst case scenario is, you go and delete your bncache.dat/Europe folder found in your D2 directory, both will be recreated upon your next login.