[CentOS] CENTOS 5.5 X86 continue get "out of memory" error?????

we just installed CENTOS 5.5 X86 (32 bits) on DELL server.  After installed we also apply lated O.S. patches.

This server have 64 GB RAM and run "2.6.18-194.26.1.el5PAE #1 SMP ".  when I doing "cp", "mv". "ftp", ....  it continue "kill" my process and pop up "out of memory" on /var/log/messages:

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Nov 24 16:36:25 MCC kernel: HighMem: 1*4kB 0*8kB 1*16kB 3210*32kB 17367*64kB 4010*128kB 2497*256kB 126*512kB 2*1024kB 0*2048kB 10549*4096kB = 45642004kB
Nov 24 16:36:25 MCC kernel: 4927968 pagecache pages
Nov 24 16:36:25 MCC kernel: Swap cache: add 0, delete 0, find 0/0, race 0+0
Nov 24 16:36:25 MCC kernel: Free swap  = 36869116kB
Nov 24 16:36:25 MCC kernel: Total swap = 36869116kB
Nov 24 16:36:25 MCC kernel: Free swap:       36869116kB
Nov 24 16:36:25 MCC kernel: 16777216 pages of RAM
Nov 24 16:36:25 MCC kernel: 16547840 pages of HIGHMEM
Nov 24 16:36:25 MCC kernel: 362985 reserved pages
Nov 24 16:36:25 MCC kernel: 3334251 pages shared
Nov 24 16:36:25 MCC kernel: 0 pages swap cached
Nov 24 16:36:25 MCC kernel: 839171 pages dirty
Nov 24 16:36:25 MCC kernel: 2 pages writeback
Nov 24 16:36:25 MCC kernel: 3528 pages mapped
Nov 24 16:36:25 MCC kernel: 59119 pages slab
Nov 24 16:36:25 MCC kernel: 584 pages pagetables
Nov 24 16:36:25 MCC kernel: Out of memory: Killed process 5114, UID 81, (dbus-daemon).
Nov 24 16:37:11 MCC gpm[5531]: *** info [client.c(137)]: 
Nov 24 16:37:11 MCC gpm[5531]: Connecting at fd 6


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any one know why?

Is CENTOS X86 5..5 really NOT stable version?

Thanks.