freebsd 7 with sata drives

[Brian]

The system gets thru the install fine, and does the next reboot ok.  
But, if I do a very simple cvsup to get freebsd 7-stable source, then a 
kernel rebuild, the system has what looks like a drive/controller 
recognition problem next time.  It sees the proper root slice of ad5s1a, 
but cant boot it.  It shows an error with sio1, unable to open device or 
something similar.  Has this been seen before?

Brian