Can't log in (WoTLK)

This problem seems kinda random for me, bcs sometimes I actually can log in, and other - I don't. Just the same problem as for some folks here: my password is correct, as well as realmlist and config realm, no "Reading only" flags.

Here is what log says:

4/2 23:04:40.569 GRUNT: state: LOGIN_STATE_CONNECTING result: LOGIN_OK
4/2 23:04:40.685 GRUNT: state: RESPONSE_CONNECTED result: LOGIN_OK 62.138.7.219:3724
4/2 23:04:40.769 GRUNT: state: LOGIN_STATE_AUTHENTICATING result: LOGIN_OK
4/2 23:04:40.855 GRUNT: state: LOGIN_STATE_FAILED result: LOGIN_DBBUSY
4/2 23:04:40.864 GRUNT: state: LOGIN_STATE_DISCONNECTED result: LOGIN_OK
4/2 23:04:40.864 GRUNT: state: LOGIN_STATE_FAILED result: DISCONNECTED

Ok, now the same problem again. Have absolutely no idea, how to fix it