7.0-CURRENT-200608-amd64 sysinstall bug?

I'm trying to install the latest -CURRENT snapshot on a PC which won't 
boot any other FreeBSD CD (any other ISO I found is missing the recent 
nVidia MCP55 ATA fixes).

After slicing/labeling, and chosing the distribution to install, 
sysinstall fails with a '/ disk full' error (ALT-F2 reveals that it was 
trying to copy /stand to /mnt/stand)

Some more info: using sysinstall I created two slices, ad4s1 (10GB) FAT, 
ad4s2 (30GB) FreeBSD. Then, inside ad4s2, I created a root FS (5GB) a 
swap partition (3GB) and a /usr FS (the remainder of the slice 22GB)
I've not assigned any mountpoint to ad4s1 (the FAT partition). The newfs 
and bootloader install was seemingly successfull (indeed, after a reboot 
the existing filesystems are recognized).

Is there something other I should try? How could I use the fix-it 
console to manually install the tarballs?

One more 'cosmetic'. I tried also installing on the slices created on a 
previous attempt (without forcing a newfs in disklabel), and sysinstall 
warned me that it was operating on a existing root filesystem, where it 
expected to find the necessary /dev entries: Is this message still valid 
now that /dev is a virtual filesystem?

Thanks for attention,

Angelo Turetta
Modena - Italy