error "Too many open files"

[Martin Minka]

Hello,
pls. advice me.

I am receiving errors from nginx of this kind:

2007/06/25 13:10:57 [alert] 8995#0: *20640082 socket() failed (24: Too 
many open files) while connecting to upstream, client: XXX.XX.XXX.XXX, 
server: XXX.XXX.XXX.XXX, URL: "/", upstream: 
"http://XXX.XXX.XXX.XXX:80/", host: "XXX.XXX.XXX.XXX"

What could be wrong ?

I am using nginx 0.6.0 and Centos 4.4.

Best regards,
Martin Minka