Also can you share your model?
I haven't used the DEM tools in version 10 yet, so these are general considerations.
Did you try inserting print statements after each critical step? At least you will figure out what exactly causes the crash. You mentioned renaming - I would use very short dataset names (starting with a letter), no slashes/underscores and other fancy symbols, location for FGDB and PGDB - just one level below root (C:\, D:\, etc), no UNC paths. Also try with a smaller subset - could be a matter of size (know this from my own bitter experience).