OS is not detected CPU and memory

Hi,

Server AIBVRFCC failed POST while booting on 06/28/2009. Server is up, but OS cannot see two CPUs (CPU 0 and CPU 2) and half of the installed system memory (8 GB is physically installed but only 4 GB is seen by OS now).

bld00016:root psrinfo
1 on-line since 06/28/09 05:51:36
3 on-line since 06/28/09 05:51:14
bld00016:root prtconf | grep Mem
Memory size: 4096 Megabytes

POST error messages on console:

{3} ok boot -r
Resetting ... 
Software Reset
WARNING: Offlining/Disabling CPU0...and CPU2...Done.
Enabling system bus....... Done
Initializing CPUs......... Done
Initializing boot memory.. Done
Initializing OpenBoot 
Probing system devices
Probing I/O buses 
screen not found. 
keyboard not found. 
Keyboard not present. Using ttya for input and output.
Probing system devices 
Probing I/O buses 
Sun Fire 880, No Keyboard
Copyright 2007 Sun Microsystems, Inc. All rights reserved. 
OpenBoot 4.22.34, 4096 MB memory installed, Serial #52259659.
Ethernet address 0:3:ba:1d:6b:4b, Host ID: 831d6b4b. 
Initializing 11MB of memory at addr b0ff002000
Initializing 16MB of memory at addr b0fe002000
Initializing 4064MB of memory at addr b000000000
ERROR: Power On Self Test Failed. Cause:
OBMD 
ERROR: POST failed.

Please suggest me

Thanks
Arum

Reseat the boards and powerup the server again. It might not be seated correctly in the slots(maybe). Unlikely that it should fail