gandalf
I'm having almost exactly the same problem. And i'm on windows 8, so yes, I don't believe it's a windows issue. If I use ASIO as my driver sonar refuses to work.  If I use wdkms it works, but locks as soon as I stop the track. This all started when I bought a focusrite interface. I was using a lexicon interface, which worked fine with sonar 8, but X3 refused to recognise it as a midi driver.  Given lexicon no longer supported this product i decided to upgrade. To be honest, I'm pretty much at the end of my rope with X3. I am NOT even remotely interested in going through many of the processes listed on here.  Sonar need to make a program that simply works once installed (with maybe a few tweaks).  I've never used any daw but sonar, and up until about 4 months ago i used 8 without any dramas (apart from the usual sonar instability).  Since changing to x3 it's been a constant nightmare. I HATE what they've done with the selection tool, which constantly has me searching the online manuals for how to do the most basic of processes, and it's just miles too glitchy. I'll download the updates today and try them, but if they don't fix the problem I'm done.  Really annoys me, as this is not a cheap program, and i loved sonar 5 and 8, they were so user friendly.  For years the customer base has been asking sonar for nothing but a more stable program, and here, it appears they've released the most unstable version yet.  STOP with adding plug ins etc, and just MAKE IT STABLE.  Was at a friends place the other day and he was using a daw i've never even heard and it didn't crash, glitch, or lock up once, and he knows next to nothing about daws, he simply installed it and ran it.  And it works.  Is that really so hard SONAR?

Yup.

Old thread alert (@jonnewyork this is not helpful you have your own thread and nothing here is related to your current issue, please let off steam somewhere else).

tKx5050
OP, if you haven't already, take a few minutes and uninstall/reinstall your audio interface drivers/software. These hangs are almost always a resolute of the audio driver acting weird. On my system the new Realplayer cloud app causes sonar to not load so I can't let realplayer update itself.

+100. though didn't have to uninstall / reinstall anything.
Last night I got panicked as Sonar X3e wouldn't get past the startup splash screen, even after two PC reboots. So I googled and found this post. I then unplugged my USB audio interface and USB midi keyboard, launched Sonar -- which did launch -- then exited, replugged in my USB gear, relaunched, and all was ok again. Big thanks, txk5050!!

Sometime my Sonar X3 had the same symptoms, but in my case was simple, I use two video monitors and I had forgotten that the last time I used Sonar I had left it active only in the monitor 2 ... And I forgot to turn on monitor 2 ... and it was there all the time ...

So, not being a computer geek of any kind... I have never heard of a "cold reboot" I Googled it and I think I understand, just unplug all power (I use a strip/protector as I assume most do), unplug or turn that off and back on, or unplug/replug it to the wall?  Of course, I will try log off/log back on first if I get a problem like this. I do use an Octa-Capture. I am subscribing to this thread so I wont forget... I understand a problem like this is a nightmare and I hope you get it sorted out.
I might add (I don't know if it will help with this) going all 64bit really seems to help with X3 forward. 
I stay away from 32bit as much as possible.
Sorry for your problems but thanks for this thread.

After upgrading to Win. 10 Sonar X1 LE won't open any former projects. Registry problem? Any ideas?
Dave Clayton

This thread is many years old and describing a different problem.

Please start a thread of your own.