What are the products of the haloform reaction of acetylacetone?
Because acetylacetone is a 1,3-dione, the carbonyls are very enolizable.  This makes the hydrogens attached to carbon 3 on acetylacetone very acidic.  When introducing the conditions for a haloform reaction, base is added.  The base will take carbon 3's hydrogens, in the presence of some halogen, they will be replaced, this happens twice.  Now, with the product 3,3-dihalopentane-2,4-dione, the reaction will end.

If you insist on a haloform reaction occurring, a much stronger base will be needed and the reaction vessel would probably need to be heated.  It will proceed as usual and create first 2,2-dihalo-3-oxobutanoic acid (2,2-dihaloacetoacetic acid). The reaction will probably stop at this point. Upon heating though, this compound may decarboxylate to give 1,1-dihaloacetone and carbon dioxide. If you wanted to continue with this, you could do another haloform reaction to first generate perhaloacetone, and if you wanted to, this may be able to become trihaloethanoic acid and haloform.  

But realistically, the reaction would end at the 2,2-disubstituted dihalo acetoacetic acid (2,2-dihalo-3-oxobutanoic acid)