This is why Yamaha and Roland now offer optional 'full support' drivers for their models that hype DAW integration. What works for one person will not work for another, even though they have identical set ups, or what works one time for one person will not work the next, again with the same set up. Sorry off topic here but that's sometimes how i find solutions-by reading about other's difficulties! You are not off-topic at all! I noticed this with the XW-P1 using the USB to computer connection-it definitely had trouble transferring complete banks of sounds, performances and package files in one pass from the computer to the XW with the XW data manager and again i could only guess it was due to the necessary use of the class complaint driver.

And I am again guessing that the IDES programs, needing quite a bit of buffer memory to transfer large sysex files are giving some of us trouble.

I guessed my problems were being caused by lack of buffer memory-a problem I hadn't experienced in a long time with standard midi din cables and more recent Windows midi drivers but was experiencing with the USB to computer 'class compliant' driver. Hey thanks Ted, just came across this post out of curiosity and it clarified the difficulties i experienced with these USB/midi computer cables and the PX350. For me, I just limit my file transfers to no more than 15 files at a time.

Yamaha usb midi driver windows 7