CentOS - Apr 2007 - Error trying to mount NFS volume from kickstart in CentOS 5

The post section of the kickstart configuration file I have been  
using in CentOS4 looks like this:

   %post
   mount centosmirror:/var/www/html/ks /mnt
   /mnt/ks/post/post.sh > /root/post_install.log 2>&1
   umount /mnt

I tried to do my first CentOS 5 kickstart installation today using an  
identical post section, but the post install script did not run.   
After instrumenting the kickstart a bit, I found that the above mount  
command failed with the following error message:

   mount.nfs: Input/output error

Not a very helpful error message -- any clues as to what is going  
on?  It's a little tricky and time consuming to debug kickstart  
problems like these, so I thought I'd ask the list and hopefully save  
some time.  If I execute that mount command after rebooting the  
system, it works just fine.

Thanks,
Alfred

I'll follow up my original post with some more details (no solution  
yet, though).  The problem is that when I try to do an NFS mount  
during the post section of the kickstart, I get the following error:

   mount.nfs: Input/output error

I modified my kickstart script to not shut down, and when the install  
completed, I fit Ctrl-Alt-F2 to get to the console.  I typed the  
exact same mount command and it worked.  Then I did a "chroot /mnt/ 
sysimage" and tried the mount command again.  This time it failed  
with the same error and it takes almost 2 minutes for it to time  
out.  Here are the last few lines from an strace of the mount:

11:07:07.320919 lstat64("/etc/mtab", {st_mode=S_IFREG|0644,  
st_size=24, ...}) = 0
11:07:07.321019 stat64("centosmirror:/local/www/html", 0xbf81ead0) =  
-1 ENOENT (No such file or directory)
11:07:07.321093 stat64("/sbin/mount.nfs", {st_mode=S_IFREG|S_ISUID| 
0755, st_size=55012, ...}) = 0
11:07:07.321195 clone(child_stack=0, flags=CLONE_CHILD_CLEARTID| 
CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0xb7ff1928) = 4981
11:07:07.323011 wait4(-1, [{WIFEXITED(s) && WEXITSTATUS(s) == 32}],  
0, NULL) = 4981
11:08:52.343024 --- SIGCHLD (Child exited) @ 0 (0) ---
11:08:52.343135 exit_group(32)          = ?

Have there been some changes to the mount command in CentOS 5 that  
are causing this problem?  Anyone else successfully mounted an NFS  
share in the %post section of a kickstart script?

Alfred