I've run into this exact same problem yesterday, and actually popped online to post about it. What a coincidence. Anyways, what happened to me was that I was running Sonar XL2.0 just perfectly last week with DX8.1. Then I had a catastrophic system file error and had to transfer all vital files over to the other physical hard drive and reinstall Win2000 and all the applications. I then read an interesting thread about these "KX-something" drivers for SB cards that will, among other things, get quite reasonable latency numbers (something all us SB users have struggled with in the past). So I went to install them, and it required that you had the most recent DirectX. So I downloaded 9.0, installed, then chickened out on the KX drivers when I read some of the info, and something about only mono soundfont support and causing periodic sudden restarting of Windows (something I had seen before on my system shortly before the big bang). Man I'm long winded. Anyhoo, I go to install Sonar, and it says it needs 8.1. So I go to uninstall 9.0, and I can't figure it out for the life of me how to, apart from deleting the individual .dll files (scary me thinks...). So I try to install 8.1 from Sonar, and of course, since 9.0 is already on there it runs for 2.3 seconds and says its all done (and really its done nothing at all but notice I already had a newer version installed then automatically quit).
I figure the Sonar people HAVE to notice this and provide us with a patch or something, and soon!
Don't use it for sure.
