[CentOS] Radeon driver under CentOS-6

I wonder if anyone has CentOS-6 working on an HP MicroServer?
I'm having a problem with the graphics driver
for the Radeon HD 4200 graphics card.

CentOS-5.6 is working fine on this machine;
but at present I only have CentOS-6 running in text mode.

The graphics card as given by "/sbin/lspci -m" is
-------------------------------
01:05.0 "VGA compatible controller" "ATI Technologies Inc" "M880G [Mobility 
Radeon HD 4200]" "Hewlett-Packard Company" "Device 1609"
-------------------------------

The Radeon related modules are
-------------------------------
[tim at grover ~]$ lsmod | grep -i radeon
radeon                798300  0
ttm                    47134  1 radeon
drm_kms_helper         32113  1 radeon
drm                   202185  3 radeon,ttm,drm_kms_helper
i2c_algo_bit            5664  1 radeon
i2c_core               31274  5 
i2c_piix4,radeon,drm_kms_helper,drm,i2c_algo_bit
-------------------------------

Under CentOS-5.6 the Radeon related modules are
-------------------------------
[tim at grover ~]$ lsmod | grep -i radeon
radeon                148193  0
drm                   115561  1 radeon
-------------------------------

Admittedly I have probably installed different packages
in the two cases.

I'm wondering if I could try the old radeon module,
and if so how?

Are there any documents that might help me
determine the problem, and hopefully solve it?

I don't see any errors listed in /var/log/messages, or in dmesg.

Any suggestions or advice gratefully received.






-- 
Timothy Murphy  
e-mail: gayleard /at/ eircom.net
tel: +353-86-2336090, +353-1-2842366
s-mail: School of Mathematics, Trinity College, Dublin 2, Ireland