Can't *write* to a hard disk, problem related to GEOM(4)?

Hello,

I post to current_at_, since the problem *seems* to be related to GEOM.

The first thread for this subject begin from question_at_, you can read it
here:
 http://lists.freebsd.org/mailman/htdig/freebsd-questions/2004-April/\
 thread.html#43212

I can resume my problem like that:
 - My OS release is FreeBSD 5.2.1-RELEASE-p4;
 - The disk is a 120Go/8Mo from Maxtor (UDMA133);
 - What dmesg(8) says about it:
    # grep ad10 /var/run/dmesg.boot
    GEOM: create disk ad10 dp=0xc6ab2660
    ad10: 117246MB <Maxtor 6Y120P0> [238216/16/63] at ata5-master UDMA133
 - But when I tried to create a slice on it, I get:
    # fdisk -BI ad10
    ******* Working on device /dev/ad10 *******
    fdisk: can't write fdisk partition table: Operation not permitted

/dev/ad10 was previously part of a hardware miror (ar(4) device with a
HighPoint HPT374 (channel 2+3) UDMA133 controller), but since it was
broken for an unknown reason, thid drive is no more usable, even alone.
For example, I am not be able to create a new slice on it.

1/ I try to set the sysctl "kern.geom.debugflags" to 16, in order to
   write to it... without success.

2/ I succeed to write on it under the 4.9 bootable CDROM (fdisk, bsdlabel,
   etc.) but when I reboot under the installed FreeBSD-5.2.1 I cannot
   access it any more again.

It seems that 'Joan Picanyol i Puig' was in the right direction arguing
to play with "kern.geom.debugflags", but it didn't work for me. If someone
has an other idea to try to recover this drive...

Thanks,
-- 
-jpeg.