Error: 1.8.4 agent can't restart

[Gytis]

After upgrade to 1.8.4, agentd can't restart:

8991:20110316:160347.242 Zabbix Agent started. Zabbix 1.8.4 (revision 16604).
8991:20110316:160347.242 Listener failed with error: bind() for [[-]:10050] failed with error 98: Address already in use.

What might be wrong?

[Gytis]

Any ideas why restart or stop/start fails?