I would be willing to bet it's one of those handle index failures.
I want you to change the dwarf. Only the STUPIDEST dwarf players ever die and when they do, it was either by full out gank, or an ownage Conservator Janise
The Dwarf is quite killable, you just need the right strategy.
Don't tank him, ever. Slows and disables rape him badly, so does Greel's Caress.
Also, he had no heals whatsoever, so whatever damage you deal him is not going away unless he runs to base.
Just keep beating at him and he always dies.
I've played against him dozens of times, and even as rather fragile heroes.
It's not tough to whittle him down even at max level.