Sonar X1 Studio crashes when stopping playback

I find myself spending more time trying to figure out ways to avoid this bug than I do writing music. If anyone has any ideas for a resolution, please let me know.

In Windows 7, I'm composing using Sonar X1 Studio x64 and EWQL Symphonic Orchestra (with VST x64 plug-in). When my Sonar composition reaches a certain length of time and/or a certain number of instruments it seems, Sonar crashes if I stop playback while an instrument is playing. If I wait for a gap between instruments playing and quickly stop playback when no instrument is playing, Sonar won't crash. My initial suspicion was memory, however I have between 1.7-2.0GB of free physical memory when this happens. A crash caused by stopping playback is more likely to occur toward the end of my composition than the beginning. The crash itself is Sonar X1 "not responding." It will never catch-up and recover. Sometimes Windows asks me if I want it to report the crash or find a solution to the problem (which it never does of course).

Here are some system specifics.
Windows 7 Home Premium x64
Intel Core i5-2410M @2.30 Ghz, 2301 MHz, 2 cores, 4 logical processors
Installed memory: 8GB
EWQL Symphonic Orchestra (PLAY edition) x64 (v3.0.32)
EWQLSO is stored on 7200 rpm 500Gb HD (282 Gb free space remaining on E:)
Operating system and Sonar stored on 5400 rpm 500 Gb HD (389 Gb free space remaining on C:)
Sound: Motu Audio Express via USB
Sonar X1 Studio x64 (X1d build 534)
Sonar composition file: 1.25 MB file, 4m:48s composition length, 3 soft synths, 32 MIDI tracks

During playback:
CPU 0=50%, CPU 1=10%, CPU 2=40%, CPU 3=5%
Used physical memory: 40%, Commit charge=25%
Disk queue length: C=0.05, occasionally > 0.1

I did successfully reproduce this error only once when I created a new file, added 3 software synths and 32 MIDI tracks and performed the following: (1) I armed all MIDI tracks and recorded a single note at 0m:00s lasting one second; (2) armed all MIDI tracks and recorded a single note around 4m:00s lasting one second; (3) started playback at 3m:55s; (4) stopped playback when the notes sounded and, (5) watched Sonar crash.

Thanks!
John

Hi Fog. Thanks for your response.

-Changing the playback IO buffer size has no effect

-I'm in ASIO mode on both the MOTU device and in Sonar; Sonar crashes regardless of whether Sonar is in ASIO or WDM/KS mode

-MOTU connects via high-speed USB directly to computer

-MOTU's settings match Sonar's settings

-My internal sound card is disabled

-There are no IRQ conflicts

Here are some Sonar configuration details:

Audio driver bit depth: 24 (64-bit double precision engine)

sample rate: 44100

Buffers in playback queue: 2 (uneditable because of ASIO)

Buffer size: 1024 samples (uneditable because of ASIO)

Driver mode: ASIO (Dithering: Triangular)

File system: Enable read caching: Disabled (enabling and increasing buffer size has no effect)

Playback: Prepare using 1000 Millisecond buffers (increasing this value has no effect)

Thanks.

John

Stay in ASIO mode first. There is some tailoring that needs to be done between the audio buffer and the I/O buffers. I had my ASIO buffer too high the other day and FastBikerBoy sent me back a nice PM on this:
 
   Start with the ASIO buffer at 128 (Preferences->Audio->Driver Settings->ASIO Panel...), and I/O buffers at 512 (Advanced Mode: Preferences->Audio->Synch and Caching)

• Set preferred audio buffer.
• Start playback.
• If it drops out or other issues adjust I/O buffers. Try 512 for both as a starting point.
• Repeat steps 2 & 3. Try adjusting buffers both up and down until happy. 256 jumps should do.
• If after trying all sizes up to 1024 you still have issues go back to step 1 and increase audio buffer.
• Repeat as necessary  until you find the "magic" combination for your setup.

   I was having repeatable dropout and was because this was too high. The 128 audio and 512 for I/O was the "magic" combo for me.