hey Warren-
check this out:
https://forums.creativecow.net/thread/8/980738
might be that even though you have all the P2 media stored on a single
FW800 drive, you are not loading all the individual folders which contain the spanned clips when you L&T?
try working with only one spanned clip at a time, and not multiple.
make sure you have selected just the individual folders containing
the spanned clips and not the entire volume.
perhaps your clips are damaged and will need to be repaired using the
camera that created them.
just some more thoughts…