KDM & sessions default

[daves selby <dave_arahan@yahoo.co.uk>]

I use KDM as a graphical login manager, which selects KDE, Gnome etc etc

I go into KDE, go into the control center, modify sessions delete some 
sessions and add Fluxbox.
In /etc/kde2/kdm/kdmrc, I get ....

MinShowUID=1000
NoUsers=adm,alias,amanda,apache,bin,bind,daemon,exim,falken,ftp,games,gdm,gopher,halt,httpd,ident,ingres,kmem,lp,mail,mailnull,ma
n,mta,mysql,named,news,nobody,nscd,operator,pcap,pop,postfix,postgres,qmaild,qmaill,qmailp,qmailq,qmailr,qmails,reboot,rpc,rpcuse
r,rpm,sendmail,shutdown,sympa,sync,tty,uucp,xfs,xten,
PreselectUser=None
SessionTypes=Fluxbox,gnome-session,kde2,failsafe,
ShowUsers=Selected
SortUsers=true
StdFont=helvetica,12,5,0,50,0
Users=root,test,

It all works great, I can login with KDE, Fluxbox, Gnome all AOK

However, frequently, when I re-boot Debian, or even logout back to KDM, the 
session file seems to default to ...

MinShowUID=1000
NoUsers=adm,alias,amanda,apache,bin,bind,daemon,exim,falken,ftp,games,gdm,gopher,halt,httpd,ident,ingres,kmem,lp,mail,mailnull,ma
n,mta,mysql,named,news,nobody,nscd,operator,pcap,pop,postfix,postgres,qmaild,qmaill,qmailp,qmailq,qmailr,qmails,reboot,rpc,rpcuse
r,rpm,sendmail,shutdown,sympa,sync,tty,uucp,xfs,xten,
PreselectUser=None
SessionTypes=default,twm,sawfish,xfwm,gnome-session,kde2,failsafe
ShowUsers=Selected
SortUsers=true
StdFont=helvetica,12,5,0,50,0
Users=root,test,

I loose my Fluxbox session and re-gain all the original sessions.

I have edited /etc/kde2/kdm/kdmrc directly with vi, it works then defaults 
again !!

I have edited kdmrc then removed write permissions, chmod a=-w kdmrc
it works then defaults again !!

One clue, though I dont know what to do with it, kdm.options contains ..

# /etc/kde2/kdm/kdm.options
#
# configuration options for kdm
# See kdm.options(5) for an explanation of the available options.

no-ignore-nologin
no-restart-on-upgrade
no-run-xconsole
use-sessreg
generate-sessiontypes

The last line, generate-sessiontypes, could be a clue.
I tried
man kdm.options(5)
no go ??? 

Any idea where the kdm.options(5) help file is ?
Any idea why kdmrc defaults ?

All help much appreciated.


**PS
I have not uploaded any updates from debian. My winmodem driver wont compile 
in debian, havent sorted this one out yet !!!!