Hello,
 
Lately I am facing a problem with the fast bounce audio export / bounce to track. It started all of a sudden with no apparent reason (I didn't made any changes/update to my system). The problem is that when I export / bounce to track a vst instrument (with fast bounce), Sonar cuts the length of each and every note played. When eχport / bounce to track the same track at real time (unchecked fast bounce) everything is ok. I have attached an image with the two waveforms (1st with fast bounce, 2nd with real time, just played 3 chords on ivory piano). 
 
Has anyone faced the same problem? 
 
I run Sonar X3e Producer (64bit) with a Presonus Firebox (firewire) sound card, on a Windows 7 ultimate (sp1) system, Intel Core 2 Quad cpu Q9650 @ 3.00GHz, Asus P5E-VM HDMI motherboard, 256GB Samsung SSD drive for windows, programs and libraries and another one SSD drive for audio data and 8 GB of RAM.
 

Just ivory? Are the three wav chords in the 1st picture the same length? It's almost like a hard gate. Pretty weird.

The same weird behavior happens also with the Spectrasonic Trilian, and others vst.

What happens with a long loud string patch?

With a long string from omnisphere it's ok.
With 3 chord from Lounge Lizard it's ok.
With 3 chord from Akoustik piano it's ok.
With the same midi track to Ivory, cutting the notes....
 

What happens with a real time bounce?

Everything are sounds great!

Do you use any hardware that goes "outside the box," like a Universal Audio card or SSL Duende?

Nothing "outside the box".

Midi Buffers?