[CentOS] problem clamd via rpmforge

hello list
hello centos network
hello all the builder of rpm's

i use clamd package via rpmforge
today they are passes
i use CentOS 5.5 with small system with low memory
system support couple 
postfix/amavisd/clamd/dkimproxy/sid-milter/policyd/postgrey/dovecot2

when i restart clamd i obtain one error
i quote for clarity

~]# service clamd restart
Stopping Clam AntiVirus Daemon:       [  OK  ]
Starting Clam AntiVirus Daemon: WARNING: Running on 32-bit system, and 
RLIMIT_DATA > 2GB, lowering to 2GB!
                                      [  OK  ]


what error RLIMIT_DATA > 2GB
i use 1GB swap

how to configure the machine to remove this error


thanks for all return