Bizarre Diskless Boot Behavior

[Jeff Wheelhouse]

I have a number of diskless FreeBSD servers.  Usually, they work  
fine.  But sometimes when I reboot one, I get weird messages on the  
console like this:

FreeBSD/i386 bootstrap loader, Revision 1.1
(root at e2, Sat Jan 19 16:41:40 MST 2008)
pxe_open: server addr: 1.2.3.4
pxe_open: server path: /path/to/NFS/Root
pxe_open: gateway ip:  1.2.3.1
\
Insert disk labelled Loader.rc and press any key...

It isn't always "Loader.rc" though, it seems quasi-random.  I've also  
seen:

Insert disk labelled ELF and press any key...
Insert disk labelled boot.nfsroot.options="nfsv3,soft,intr,tcp" and  
press any key...

(The latter being the first line of loader.conf.)

I think these incidents correspond to the following strange xferlog  
entries from tftpd on the boot server:

Jul 30 20:15:03 xx tftpd[86096]: 1.2.3.11: read request for \.split:  
File not found
Jul 30 20:15:03 xx tftpd[86098]: 1.2.3.11: read request for \.split:  
File not found
Jul 30 20:15:03 xx tftpd[86100]: 1.2.3.11: read request for  
\.gz.split: File not found
Jul 30 20:15:03 xx tftpd[86102]: 1.2.3.11: read request for \.gz: File  
not found
Jul 30 20:15:03 xx tftpd[86104]: 1.2.3.11: read request for \: File  
not found

Rebooting generally makes it go away, so it's not a *big* deal, but I  
wouldn't want this to happen in the event of an unattended panic/ 
reboot or something.  Does anyone have any ideas what might cause this?

Thanks!

Jeff