wow, I feel stupid now..
Okay, when I call mysql_async_create_query_nosave() once, all other queries (even normal async ones) fail to execute, I have to shut the server down (close the terminal/screen), a normal /killserver doesn't help
But its just a note, I don't get it why one would use nosave when you do not get any result back? Maybe its just some mysql internals with this store