I created a new empty project with one MIDI region set to Yamaha Piano Hall. I created two new notes, both at 1 1 1 1: D3 and F2. On piano roll playback, the F2 comes in just before the D3. I'd say, about 25 milliseconds too soon. The bounced AIFF is here: http://soundcloud.com/kendracute/output-1-2 . This appears to be another sampling bug in Yamaha Piano Hall (I posted about another sample bug in another thread). The chord sounds fine using "EXS Grand Piano" which is under the "Garage Band" instruments in the instrument selection menu, but that instrument has other problems.