Hi,
I know it's about one year later than the original post, but I'm having the exact same problems as you described here... In google-user groups I read that one needs to go back to the beginning of the land use / soil / slope definitions and delete all created HRU associated files. Having done that, the problem wasn't solved, the same message popped up again.
Have you figured out a working solution to this issue yet?
Thanks for any help / suggestions!
Andy