Error with Thread

[Jean Carlos Oliveira Guandalini]

Hello, i'm using version 1.1.8, my OS is Linux (Gentoo).

My server stop and log this:
Error: FATAL: Thread create failed: Resource temporarily unavailable

Before this log, have:
Wed Jun 29 00:16:13 2011 : Error: Dropping conflicting packet from
client client1:41250 - ID: 195 due to unfinished request 155365
Wed Jun 29 00:16:13 2011 : Error: Dropping conflicting packet from
client client2:59253 - ID: 235 due to unfinished request 155374

My config for start server is:

start_servers = 200
max_servers = 200
min_spare_servers = 10
max_spare_servers = 200
max_requests_per_server = 0

The server only returns if I restart the service

Thanks

Jean