nfs freezing programs

[Didier]

hello,

i am running ubuntu hoary and have following problems with nfs. i can mount 
folders, i can read but modifying and saving files freezes the programs i run 
on nfs shared files. when i stop or restart the system it will freeze on 
"rebooting or stopping system please wait....." this is not gonna move 
anymore. there i have to switch off or reset the box.

beneath i add my /etc/exports, /etc/hosts.allow, /etc/hosts.deny files and the 
result of rpcinfo -p on my file server machine and my /etc/fstab file and the 
result rpcinfo -p on the client machines. 

for your information i settled the users and group id to 1002 on the server as 
on the clients.

any help would be much appreciated.

didier

nfs-server /etc/exports
-----------------------------------
/home/randria/randria1 192.168.123.0/255.255.255.0(rw,sync,root_squash)
/home/randria/randria2 192.168.123.0/255.255.255.0(ro,sync,root_squash)

nfs-server /etc/hosts.allow
-----------------------------------------
sshd: .randria.com
portmap: .randria.com
mountd: .randria.com
rquotad: .randria.com
statd: .randria.com
lockd: .randria.com
nfsd: .randria.com

nfs-server /etc/hosts.deny
---------------------------------------
ALL: PARANOID

rpcinfo -p
---------------
program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper
    100024    1   udp    877  status
    100024    1   tcp    880  status
    100003    2   udp   2049  nfs
    100003    3   udp   2049  nfs
    100003    4   udp   2049  nfs
    100003    2   tcp   2049  nfs
    100003    3   tcp   2049  nfs
    100003    4   tcp   2049  nfs
    100021    1   udp  32771  nlockmgr
    100021    3   udp  32771  nlockmgr
    100021    4   udp  32771  nlockmgr
    100021    1   tcp  32775  nlockmgr
    100021    3   tcp  32775  nlockmgr
    100021    4   tcp  32775  nlockmgr
    100005    1   udp    861  mountd
    100005    1   tcp    864  mountd
    100005    2   udp    861  mountd
    100005    2   tcp    864  mountd
    100005    3   udp    861  mountd
    100005    3   tcp    864  mountd

/etc/fstab on my client machine
--------------------------------------------------
192.168.123.1:/home/randria/randria1   /home/randria/randria1 nfs     
rw,hard,intr    0       0
192.168.123.1:/home/randria/randria2     /home/randria/randria2 nfs     
ro,hard,intr    0       0

thanks to note that i do have exactly the same folders on the server as on the 
clients.

rpcinfo -p on my client machine
--------------------------------------------------
 program vers proto   port
    100000    2   tcp    111  portmapper
    100000    2   udp    111  portmapper
    100024    1   udp    825  status
    100024    1   tcp    828  status
    100021    1   udp  32769  nlockmgr
    100021    3   udp  32769  nlockmgr
    100021    4   udp  32769  nlockmgr
    100021    1   tcp  32774  nlockmgr
    100021    3   tcp  32774  nlockmgr
    100021    4   tcp  32774  nlockmgr