i saw another post similar to my problem but several years old so I decided to make new question.

My problem is this.

I have a surface that is imported from a stp file. no problems. Made a few modifications, added a mold flange (very complex), added sides and bottom and made solid, then split into a few pieces for milling plugs, all is well.
   Since i am dealing with non-english speaking workers  i have to model and show everything, So I  model in the stock blocks and bases (w/o merge) for milling and adding multiple configurations (6) to show diferent sections on a drawing. total features 151.

For some strange reason at this point the very first knit fails on some of the configurations, then a few more rebuilds and it fails on all of them. This knit is the 3rd feature in the tree and is not supressed in any configs.

I had a similar problem with another imported surface model and had to fix it by re-importing the surface into a new part. Then inserting the new part into the model and remodeling to reference the new surface. but this model has MANY more features and that would mean much more work. and tedious at that.

I have had to use the backup files to recover the file and the file i am attaching does not have the fault so it will be interesting to see if it occurs in someone elses computer.
  the very first knit is the problem.

i am using SW 2009 sp3  (sp0 on another computer)

any help welcome.