First I got a reply from tech support. Basically, it said "can't help -that's how it works. I'll pass it on to product development."
Which is what I expected.
I'm surprised by the abrasive nature of a few of the replies to my comments here. I'm not out to destroy Sonar. It's the horse I have backed and I want to see it win. It won't do that if we ignore its defects and pretend everything is fine. The metronome issues alone prevent me from giving Sonar an unqualified recommendation to those currently using hardware multitracks.
Back to midi driver sharing. I just tested Cool Edit Pro 2. Not a true midi sequencer, but it can be made to use midi ports for midi file playback and remote control etc. With the same midi ports in use by CEP2, I opened Johnson J-edit and both apps worked fine.
Moskus. Thanks for the link- I never heard of that Cakewalk multiclient thingy- but it applied only to win9x and mme drivers (I read somewhere that seperate MPU401 driver types are not allowed in WDM). XP and WDM are more advanced. Driver sharing is a standard feature. It is Sonars design that is deliberately preventing sharing. With device sharing enabled, Sonar is quite willing to allow a wav editor to use the same audio driver but notice that the editor app doesn't have to be told to share? That's because sharing is default behaviour. Sonar is the odd one out. I can only suspect it refuses to share midi in order to protect against timing problems that might happen if another program had a lot of midi activity while Sonar is running.
About the cache thing - it really is no biggy. But I also had the same prob under win2k but never under win98SE. Incidentally, If you disable Write caching in the drives hardware properties - as recommended in several XP optimisation articles - this also causes warning logs "The driver has disabled write caching on device...". Does it again when Sonar opens and closes but this time "Sonar.exe has....". They are only warnings - not errors but I wonder why? And yes, I am familiar with optimisation techniques - sometimes wonder if I've optimised too much
. At least if it does crash - any recordings are still in the audio folder thanks to caching being disabled.
James - I have let it go. But it hurt.
Cheers