Panic - ffs_valloc: dup alloc

Hi All:

I am having a major problem on current at the moment, and I could really 
use some help.  I am at R253966 on amd64, my problem is the machine is 
panicing with: ffs_valloc: dup alloc

I have booted into single user mode and run fsck, it reports that it has 
fixed the file system but I still am getting the panic.  I did an svn 
update to 254204 and tried to buildworld and the machine panics and 
reboots. If I try startx the machine reboots with no message on the 
console.  Please let me know what info to provide to troubleshoot this. 
Any help is greatly appreciated.

Thanks in advance.