DP8 and stuck notes

[Musher]

I have been wrestling with stuck notes and I am hoping someone can tell me what to try next.

During playback from DP 8.05 on my Win7 PC, two old synths (Kawai K4 and Alesis D4) suffer from stuck notes. I can usually hear the issue, but the Kawai has a feature that makes it obvious even when I don't hear it: a MIDI activity indicator will get stuck in the on position. Pressing the Panic button on my MIDI Express XT USB clears it.

Each synth uses its own port on my MIDI Express XT USB. I do not use MIDI Thru, and so there is nothing connected to the K4's MIDI Thru port, the the MIDI Thru setting in the D4 is off.

I thought I might have a USB issue on my PC, so I did some system maintenance and cleaned up my USB devices. I switched my 828mk3 from a USB 2.0 port to a Firewire connection. I uninstalled and then re-installed MOTO's "Universal MIDI Installer" to make sure I had the latest version of the appropriate MIDI drivers.

The PC is relatively new and the OS was installed from MS disks so it doesn't have crapware. I'm a software engineer and pretty familiar with system admin and maintenance and overall the system is clean.

I thought that digital audio might be causing a problem even though my project didn't have a lot of digital tracks and/or effects and the DP8.05 CPU meter did not indicate an issue. I turned off the MOTU Audio System to use DP8.05 in "MIDI only" mode, but that didn't help.

As an aside, I also measured DPC latency to see if either the digital audio drivers or some other device driver was causing a problem. According to the DPC Latency Checker (v1.3.0), my PC "should be able to handle real-time streaming of audio and/or video data without drop-outs." I know that doesn't mean there are no driver-related issues, but it seems there is no obvious problem in that area.

To make sure the problem was not specific to the project I was working on when I noticed it, I used Band in a Box (BIAB) to make a comp sequence with MIDI piano, bass, and drum parts (no audio tracks, all MIDI). When I played the sequence via BIAB, there were no stuck notes. When I saved the BIAB sequence to a ".mid" file and played that via DP8.05, there were stuck notes.

That's where I am now. Given the steps I have taken so far, I think DP8.05 is at fault, or at least, I don't think it's the USB subsystem on my PC and I don't think it's the MIDI Express XT USB or either of the sound modules.

One last bit of info: I am not sure that my current setup ever functioned without stuck notes. My home studio was unused for the last several years. I was using an old OS9 Mac and I decided to switch to a PC, upgrade some old gear, and put other things back in order. Everything is working pretty well, except for this stuck notes problem.

Any suggestions?