Just tried quick compose for first time ever and it went through. Is yours from long pressing search button? If so, is handcent set as default for that or do you get a menu? I chose it from four options. Don't have any program set as default for doing that action.
Maybe that could be it, if its set as default. Do you run PowerStrip too? That is one of the menu options for me when long pressing search button. Vlingo and stock voice search are the other two.
It's not set as the default as far as long pressing the search button. I didn't want to give up its ability to voice search. Maybe it's the Hero showing age. Sucks, too, because that's one of my favorite Handcent features.