After trying Elastix 2RC3, I got problems after first update, so I installed 1.6.2RC2 and the same happens.
I have 2 cards: TDM800P (8 FXO modules) and a HFC ISDN card.
Without doing any config, I just :

install from CD
detects TDM800P and gives usual ISDN message (Elastix hardware detection)
do a /etc/init.d/dahdi restart (all fine)
do a yum (default repos)
do a /etc/init.s/dahdi restart
modules fail like below, Elastix hardware detection detects no cards.

I tried to rebuild dadhi, kernel, whatever but could not get it to work.
Tried reinstalling about 10 times with 2.0RC3 and 1.6.2RC2 but everytime after 1st yum update, this hapens. I suspect it is because of the ISDN card.

ANYONE HAVE A FIX FOR THIS? I'VE READ EVERY DADHI/ISDN SITE/FORUM I COULD FIND, BUT NOTHING SEEMED TO HELP. (No, this is not shouting, just compensating for weak bold )

/etc/init.d/dahdi restart
Unloading DAHDI hardware modules: ERROR: Module wctdm24xxp is in use
ERROR: Module wctdm24xxp is in use
ERROR: Module dahdi_voicebus is in use by wctdm24xxp
ERROR: Module dahdi_echocan_oslec is in use
ERROR: Module dahdi is in use by dahdi_echocan_oslec,wctdm24xxp,dahdi_voicebus
ERROR: Module dahdi_echocan_oslec is in use
ERROR: Module echo is in use by dahdi_echocan_oslec
error
Loading DAHDI hardware modules:
FATAL: Module dahdi not found.
wct4xxp: FATAL: Module wct4xxp not found. [FAILED]
opvxd115: FATAL: Module opvxd115 not found. [FAILED]
wcte12xp: FATAL: Module wcte12xp not found. [FAILED]
wct1xxp: FATAL: Module wct1xxp not found. [FAILED]
wcte11xp: FATAL: Module wcte11xp not found. [FAILED]
wctdm24xxp: FATAL: Module wctdm24xxp not found. [FAILED]
wcfxo: FATAL: Module wcfxo not found. [FAILED]
wctdm: FATAL: Module wctdm not found. [FAILED]
wcb4xxp: FATAL: Module wcb4xxp not found. [FAILED]
wctc4xxp: FATAL: Module wctc4xxp not found. [FAILED]
xpp_usb: FATAL: Module xpp_usb not found. [FAILED]
opvxa1200: FATAL: Module opvxa1200 not found. [FAILED]
ystdm8xx: FATAL: Module ystdm8xx not found. [FAILED]
ystdm16xx: FATAL: Module ystdm16xx not found. [FAILED]
ap400: FATAL: Module ap400 not found. [FAILED]
dahdi_dynamic_eth: FATAL: Module dahdi_dynamic_eth not found.[FAILED]
dahdi_dynamic_ethmf: FATAL: Module dahdi_dynamic_ethmf not found.[FAILED]
ax1600p: FATAL: Module ax1600p not found. [FAILED]
rxt1: FATAL: Module rxt1 not found. [ OK ]
r1t1: FATAL: Module r1t1 not found. [ OK ]
rcbfx: FATAL: Module rcbfx not found. [ OK ]
Running dahdi_cfg: [ OK ]



After this error, I try:
[root@voip ~]# depmod
[root@voip ~]# modprobe dahdi
FATAL: Module dahdi not found.
[root@voip ~]# modprobe wctdm24xxp
FATAL: Module wctdm24xxp not found.

[root@voip ~]# dahdi_cfg module
Notice: Configuration file is /etc/dahdi/system.conf
line 0: Unable to open master device '/dev/dahdi/ctl'


[root@voip ~]# dahdi_genconf
Empty configuration -- no spans
Empty configuration -- no spans


[root@voip ~]# dahdi_hardware
pci:0000:00:09.0 wctdm24xxp- d161:0800 Wildcard TDM800P
pci:0000:00:0b.0 zaphfc- 1397:2bd0 HFC-S ISDN BRI card

[root@voip ~]# dahdi_tool
Unable to open /dev/dahdi/ctl: No such file or directory

[root@voip ~]# dahdi_scan
Unable to open /dev/dahdi/ctl: No such file or directory

[root@voip ~]# dahdi_maint
DAHDI Tools Version - 2.3.0

Did you ever fix this issue. I am having a similar problem with dahdi.

I rolled back to kernel 2.6.18-164 and reconfigured all the dahdi stuff and its working again. Hope that helps someone

I downloaded latest Elastix install and it did not happen again.