As a Music Creator user from many years I have this week started using Sonar X1 LE which was supplied with the Roland A500 Pro controller I use. The main reason I have switched to Sonar is so that I can create and play backing tracks with 4 separate channels, and I am trying to output Sonar to a Novation nio2/4 usb interface.
When I first set up everything all seemed to be working well for a couple of days but today, when I attempted play a project, my laptop just hung and wouldn't respond, needing to be turned off and on with the power button and this has now happened several times as I've been trying to figure out what is wrong. I can always open Sonar ok, and I have learned that if I leave the A500 controller unplugged it will usually respond ok, although I sometimes get a message that the audio device is set up incorrectly but as soon as I attempt to play a project with the A500 connected I get the 'SONARLE.EXE has encountered a problem' message and the laptop hangs, which of course makes it really difficult to find what's going wrong.

My laptop is a Core 2 duo 2.0 ghz with 4gb RAM running Win XP and, as it's used solely for music, it has little else running, no wi-fi or antivirus etc. I've uninstalled/reinstalled Sonar, the nio 2/4 driver and the A500 pro driver to see if that made any difference.
I'd really appreciate help with this as it's getting very frustrating, especially as it worked flawlessly for 2 evenings and is now crashing without me making any changes. Does anyone have any ideas?
 

maybe before opening Sonar first check the Windows settings of your A500.
maybe check drivers, and check the A500 has correct settings and is working ok.
then open Sonar without opening a project, then go to Preferences and check if your A500 is there too.
 
good luck..

Have you checked for SONAR and driver updates? 

There are no updates for LE, I have it, it came with my A 49. It's super bare bones and because it's based on X1 it's sort of buggy. I played around with it for a few hours and it kept freezing on me too. This might be what's happening to you. 
And this was on the same computer I was running 8.5Pro at the time without issues, so it was defiantly the version not my system.
But the best thing about LE is you can use it to upgrade to X3. I went with Studio for only $99. as an upgrade  ..  X3 is not buggy. 
 
Download the demo of X3 and give it a try. 

I've spent a few hours on it today but due to continual hangs it's very difficult to make any progress. I have discovered that if I reinstall the sound interface driver Sonar will function OK until I close and reopen it, then it hangs as I try to play a project. If I reinstall the sound driver again, I can do it again. The interface driver is the latest version and works fine with music creator, but I can't use the 4 outputs that I want to use.
 
It does seem at the moment that my experience with Sonar has come to a premature end, as upgrading to X3 is overkill really for just playing back project files created in Music Creator. Looks like I may have to look at alternative software.

Contact Cakewalk tech support; they might be able to help. The basic SONAR is $99, but maybe they can offer an upgrade path.

Upgrade from X1 LE to X3 Studio was $99 with the sale you get in the emails, regular upgrade price is $119. But they always seem to have the sales so don't pay that.
Basic X3 was $29 on sale and regularly $49.  
But may I ask why you want X3 if you seem happy with Music Creator? Is it MC 6?   
You say just to play back the songs? That makes no sense to me.  
 
I  am pretty sure that X1 LE and Music creator 6 are almost the same. LE had a very pour selection of Synths. Coming from Producer or even Studio the Sound Center synths were very basic and not much better than MS wavetable. 
With Cakewalk mostly you get more plug ins and Soft synths the more you pay. The basic features remain the same. A few advanced functions are added as you go up the ladder. You may not need the fancy editing tools but if your using MIDI and synths you will defiantly benefit by an upgrade. . 
As I said, X1 was buggy and didn't work for me on the same computer that ran 8.5 smoothly. 
If Music Creator is working and that's all you require to make music your fine.
You can upgrade to X3 using that as well. 
 
The X 3 versions come with way better soft synths than LE or Music creator, it's a pretty good deal to get way better sounds. It's not overkill at all unless your happy with basic those GM synth sounds. 
 
 

I've been using Music Creator 5 for several years and am very happy with it as it does pretty much everything I need it to do. I use mostly 3rd party VST synths, and bounce most MIDI to audio, perhaps leaving one or two MIDI tracks and/or soft synths live which I play with the A500 controller.
 
The only reason I've been experimenting with Sonar is because Music Creator only allows two outputs whereas I'd like to use the four outputs available on the nio so I can have drums on one channel, bass on another and synths on the remaining two, hence the need for playback only from Sonar as I can import my projects from Music Creator, set the outputs and it's job done.

Something to check because I just did this inadvertently in X3 and made me realize something. I am using the A300, and if X3 is already open, and then I power on the A300, SONAR will recognize that it came online, but it will come online disabled.
 

1. Be sure the A500 is on prior to opening SONAR.
2. If you inadvertently open SONAR first, the project will adjust to remove the unseen controller, so you need to go to Edit->Preferences->MIDI->Devices and re-enable the A500.
3. The tracks that were using the A500 need to have the MIDI in routed to the A500 again. (In the Track View, select "ALL" instead of "Custom" in the dropdown at the top of that view to see I/O's for tracks.)

   Your hang may be coming from when X1 is seeing the A500 connect to the computer (mine takes several seconds for X3 to tell me). But even when I say "yes" to a new controller being found and prompted if I want to use it, I still have to enable it in MIDI devices. And then re-route it again on the affected tracks (it disappears there as well).
 
   The quickest method to resolve this if you realize if this has happened is close the project AND X1 immediately (do NOT save it), power on the A500, then reopen X1 LE and the project. If you have saved the project, you may need to go through the steps above to recover where you were.
 
    FWIW - X3 is not supported on an XP machine.

Thanks for the suggestion but it's an avenue I have already explored. I usually plug in the Nio soundcard then the A500 before starting Sonar and I've tried different sequences all to no avail, and yesterday Sonar was crashing without the A500 being connected at all. I did get it working again late last night, but it is a strange process. I open Sonar, try to play a project, and I get a message indicating that my soundcard is unavailable, or the settings are incorrect. I then go into my audio device settings and click 'OK' without making any changes and Sonar will work maybe 5 or 6 times without a hitch, then I'll close a project, open another and it will hang completely.
 
I've thought long and hard about what it could be and as, when problem started, it seemed to occur whenever I plugged in the A500 after the sound interface I am beginning to wonder whether there could be an issue with the power output at the USB ports. I'm hoping to have a powered USB hub arrive in the next couple of days which, hopefully, should confirm it or rule it out.